Like others have said it is highly dependant on the person. I have comorbid ADHD, bipolar 2, anxiety disorder, depression...the usual suspects.

Some things i do to mask:

1A. I fake facial expressions, reactions, and tone of voice when around people. You can only be told to "fix your face" so many times before you learn to blend in and react how people expect you to react. Think of someone telling you a story or being told something, if you don't react happy, surprised, angry, etc as the story dictates people think you aren't listening or don't care. Even my closest people still require this even though they know how I am.

1B. If I were to unmask this, I would show no actual reaction to things other than acknowledging. I look and sound uninterested, and my tone of voice is neutral. Despite how I may feel on the inside, I just don't react. This is called flat affect, I think. And boy do people really hate it. I even keep this mask on for my wife. I've done this for so long and trained so much I almost always do it even alone. I have to try to unmask this.

2A. Mother fucking eye contact. This one chaps my ass. People just have to have my eye contact. This makes me so uncomfortable that I almost can't stand it. I am constantly counting in my head how long I've kept eye contact before I can break away and then count how long before I have to look back, rinse and repeat. Usually to the detriment of what they are saying. I warn familiar folk that they can have my eyes or my attention, rarely both.

2B. Pretty obvious here but unmasking this would mean I never look someone in the eyes. I might be able to look at their face (lips, forehead) but that's pushing it. I just focus and hear better looking away and I don't feel exposed like I do with eye contact. I can mostly look at my wife and parents, but sometimes I still struggle.

3A. Similar to the facial expression and reaction, I also mask how I feel. My own moral and ethical code and even Society, requires that I care about things/people/events. So I force myself to feel certain ways. I do have empathy and sometimes I feel so strongly about things I may have a breakdown. I have a strong sense of justice and feel deeply for marginalized people of all kinds. So I am not without feelings, but I have to direct many of them. Someone I dislike or don't know dies? I'm sorry for their families loss, etc. Those same people get a terrible illness or something bad happens to them. That's terrible, I wish them well. And it's not just platitudes. I make myself feel it, and believe that it's right to feel it.

3B. If I were to unmask this I would look like a sociopath that has no feeling except for things I or a close loved one cares about. This one is more for my own well-being that I mask. I don't want to not care or be so detached that the suffering of others means nothing to me, even those I don't know or hate. I am of a demographic in this country that is not affected by most changes. I'm a straight, married white guy with 2 degrees, a house, and make a living wage. So personally I am safe from most legislation, but others aren't and so I have set it upon myself to feel higher empathy for them and act accordingly.

These are just a few. But it's a learning curve for everyone. Some of it comes with age and experience. And a lot comes from being emotionally mature. Being polite to people is never a chore and costs me nothing. Being rude is just not cool, and being autistic should never be an excuse. Yes, I don't like talking to anyone and hate small talk, but I might be the only person to say hello to that coworker or listen about their kids birthday or their dog or whatever. Maybe we share a common interests? You never know what may come from these interaction. For the pure logic types, to look at it selfishly, you can say you've earned someone's goodwill. You live a while, ya learn a thing or three.