Let's start with the premise that where is the confidence that a person has some kind of "true essence"? Man is a dynamic and complex thing, born to evolve; however, it can also degrade.
Generally speaking, you can learn, if you so desire, the "animal part" of a person if it "swells" well; alcohol, as noted above, inhibits and blocks nerve connections in the frontal cortex, while activating the back lobes of the brain. Which, in fact, are responsible for impulsivity, "instincts" and other not always desirable things. However, not all - if you wish, you can perfectly train your brain, and up to certain limits you can control yourself under alcohol.
Yes, but again, this is not a "true essence", it is not even a full-fledged "core ", but only, well, maximum," half. " Man is not only an animal with his instincts, but also reason and morality; if you still share the theory "A man is just an animal inside", then perhaps yes, here alcohol will help you "reach the truth" :)
Here, of course, a detailed answer from psychologists / biologists and others is needed, but I will lay out my opinion, formed empirically, of course. The first and only time when I got drunk to a state in which I am not in control, I screamed at the top of my lungs about things that give me away in many ways: politics, vegetarianism and some details of my personal life. The last point is generally funny: you will not talk about your personal / sexual life every day when you are sober. Thus, my friends only realized that my beliefs were true, because even under a degree I vehemently argued to them why I was alone beautiful in a white coat, and they were assholes.
The point is probably that you need an unclouded mind to control yourself. Every day we calculate how and with whom we will behave, what kind of mask, as they say, to put on. Alcohol blocks the active work of some areas of the brain (biologists talk about this better) - therefore we are unable to control our flow of thoughts. What a sober person has on his mind is a drunken one on his tongue.
But to the question of the essence, I will say that alcohol alone is not enough. The essence of a person is not only in chatter. Take him on a trip with tents and one bowler hat for two - yes, you will recognize his essence.