>>33882374 (OP)
If you are serious about this, the best advice I have is to get yourself a job working in the hospitality / events sector or busy retail. Particularly casual / temporary or "agency" style work where you aren't having to truly infiltrate a social hierarchy but are rather just gapfilling / numbers for a huge industry. Think things like massive football stadiums or music festivals, rather than an intimate bar with 4 regulars. Think your biggest supermarket chain rather than a small mom n pop. The bigger the company / body of staff, the better.
You aren't doing it for the money. You are doing it for the social grind. It's a constant conveyor belt of small interactions with customers and staff. Over time you build confidence in being present for people, in being friendly and each interaction is a fresh opportunity - so if the last one failed, there's no "drag" it's just insight. You learn small talk through small interactions. You learn socially appropriate banter through worksafe interactions. You learn charisma by taking notes on others - a rare insight you will get a lot of through exposure to huge numbers of people regularly. Every shift is a fresh opportunity. It will also give you access to coworkers, who sometimes, can turn out to be kind of cool and maybe wanna hang out with you.
I did these types of jobs from 19-27 and it took me from a clearly shut off, depressive, repressed autistic type to someone who frankly people act suprised when they hear I've got a diagnosis. I learned the character. I studied the mask. I refined and practiced and studied through exposure to all these interactions. In the process of doing so I began to develop my own flavour and style. At first it was very rigid and performative. After a while it felt natural and true, although still admittedly forced because I think inherent to me is the baseline of someone who doesn't want to put energy into body language, cadence or emotion.
I really hope you consider it.