What Ultra Instict is based on is something the Japanese call Mushin (No Mind) and it is a state that can be achieved and is actually something we do every day. But it can be applied to combat which is what Goku's Ultra Instinct is. Wiki pedia had this to say on it.
"Mushin in Japanese and Wuxin in Chinese (無心 "no mind") is a mental state. Zen and Daoist meditators attempt to reach this state, as well as artists and trained martial artists. They also practice this mental state during everyday activities."
This is actually something you do every day without knowing. When you type and go so fast without looking at the keyboard. You don't even know you're doing it. You're likely in some form of Ultra Instinct now...
Etymology
"The term contains the character for negation, "not" or "without" (無), along with the character for heart-mind (心). The term is shortened from mushin no shin (無心の心), a Zen expression meaning the mind without mind and is also referred to as the state of "no-mindness". That is, a mind not fixed or occupied by thought or emotion and thus open to everything. It is translated by D.T. Suzuki as "being free from mind-attachment"."
This is what the word means. It means mind without mind. It's a state where you work at 100% full capacity due to not being confined by thoughts of what you should or shouldn't do, or with ego, or with emotion.
"Mushin is achieved when a person's mind is free from thoughts of anger, fear, or ego during combat or everyday life. There is an absence of discursive thought and judgment, so the person is totally free to act and react towards an opponent without hesitation and without disturbance from such thoughts. At this point, a person relies not on what they think should be the next move, but what is their trained natural reaction (or instinct) or what is felt intuitively. It is not a state of relaxed, near-sleepfulness, however. The mind could be said to be working at a very high speed, but with no intention, plan or direction.
Some masters believe that mushin is the state where a person finally understands the uselessness of techniques and becomes truly free to move. In fact, those people will no longer even consider themselves as "fighters" but merely living beings moving through space.
On page 84 of his 1979 book Zen in the Martial Arts, Joe Hyams claimed Bruce Lee read the following quote to him, attributed to the legendary Zen master Takuan Sōhō:
The mind must always be in the state of 'flowing,' for when it stops anywhere that means the flow is interrupted and it is this interruption that is injurious to the well-being of the mind. In the case of the swordsman, it means death.
When the swordsman stands against his opponent, he is not to think of the opponent, nor of himself, nor of his enemy's sword movements. He just stands there with his sword which, forgetful of all technique, is ready only to follow the dictates of the subconscious. The man has effaced himself as the wielder of the sword. When he strikes, it is not the man but the sword in the hand of the man's subconscious that strikes."
I did not change any quote at all. Wikipedia actually used the word "Instinct". I merely emboldened it to allow you to easily notice.
"However, mushin is not just a state of mind that can be achieved during combat. Many martial artists train to achieve this state of mind during kata so that a flawless execution of moves is learned and may be repeated at any other time. Once mushin is attained through the practice or study of martial arts (although it can be accomplished through other arts or practices that refine the mind and body), the objective is to then attain this same level of complete awareness in other aspects of the practitioner's life. Dr Robert Akita claims it helps him "listen to my wife and children more closely...especially when I disagree with them, [and] in my business it has helped when I am faced with difficult decisions...."
This is what Ultra Instinct is, and you CAN achieve it. The way you read and write is a form of Ultra Instinct. The way you eat. The way you breathe. There are examples all around of how you use it. As you see, to apply UI to fighting is to actually forget technique. At this time, a combatant is no longer a "Fighter" but simply a being moving in the universe. While technique helps you move faster and more efficient, in the end, the only thing that's needed is to let your body do it's thing. You subconsciously defend yourself. When something is flying at you, what's the first thing you think? Duck. No not the animal, though on occasion that's what flying at you, you automatically dodge without knowing. That is what the greatest martial arts masters go for. Even Bruce Lee, the man famed as "The Dragon" and in my eyes, the worlds greatest martial artist understood what it meant. He even came to the point of realizing what technique was for and founded Jeet Kune Do ("The way of the intercepting fist"), a Hybrid martial arts philosophy that later became the basis for Mixed Martial Arts (MMA) fighting. Jeet Kune Do is even developed in a way that tries to attain Mushin (Or Ultra Instinct to weebs) While I doubt you want to read all about that as this is long enough, but if you desire, I'll drop the link to the style's page later.
In the end, while people say that you can never go Ultra Instinct like in the anime, the truth is, Ultra Instinct is the only form from Dragon Ball that you CAN attain. Another might be Ikari (displayed by Broly in DBS) however, we don't actually use any Great Ape powers. So, no, your hair and eyes won't turn silver, nor will you get a kick-ass aura, but more like Whis, Beerus, and most definately Master Roshi, you will be able to attain Ultra Instinct. Have fun trying, because trying is both the key and the road block to achieving it. Such is the conundrum of Mushin.
Here is the page for Jeet Kune Do.
https://en.wikipedia.org/wiki/Jeet_Kune_Do
(Also, if you survived this far, congrats. Maybe you CAN achieve it...)
P.S. When looking through wikipedia's references on it, I saw this.
Notice the red link? It says "Migatte no Gokui" Which is a direct reference to Goku's Ultra Instinct which is, in Japanese, actually called Migatte no Goku'i as opposed to Ultra Instinct like in English. And according to the ability's page, it means "Secret of Selfishness"
https://dragonball.fandom.com/wiki/Autonomous_Ultra_Instinct_(ability)