I had to do this for a customer service job I had before. I ended up basically creating an entirely new persona and masking/dissociating every interaction, but was really good with getting sales and helping people and such while doing it. I didn't realize I was doing it until one of my friends visited me at work and mentioned I was like an entirely different person there.

Well, has never worked for me. In fact, just the opposite. I can pretty much do any social thing at least once, and things might slightly improve for a while, if I do it a few times. But the more I do it, the more anxious I get, and it becomes slightly harder and harder each time, even if everything goes perfectly.
For example, I used to be scared to walk into the doctors office, but then after few visits it became normal, I could do it like nothing. But now, after many years of lots of visits, I am already shaking, like two days beforehand. And I have not even been mistreated or anything, the anxiousness just kind of builds up eventually. I have not found a solution to it, and doing therapy did not work... it just caused the same thing happen with it, too.

Like acclimatising to rollercoasters

Honestly you may need ADHD meds. I still get a lot of anxiety about social situations but it's much milder since starting meds, and it doesn't come with that adrenaline spike, I think since I already have something providing the dopamine necessary for me to feel like I can handle it. I've found my social anxiety has gone way down since starting stimulants, as well as anxiety caused by executive dysfunction and procrastination. The meds have made me feel way smoother and better regulated.