I got a job as a security guard

Dude your fine. Most of those companies are just to have a presence anyway. You’re not actually expected to do anything. You’re supposed to call the police.

Just sew some spikes onto your clothes and you'll be a cute walking mace (like a swinging medieval mace), no one will cross you then.

what is your other job?

Depends on the position. Alot of trucking companies hire security guards to sit in a shack all day and buzz truckers in at the gate. You dont need to even be able to walk

That depends is it armed security or unarmed? Unarmed is chill as fuck. Armed be ready to fight. Your gonna deal with some fucking crazies. If you can handle that go for it. Unarmed usually chill as hell though. Worst you Dea with is Karen. At least in my experiences.

As a security guard, at best you are paid to be observant. Guard doesnt mean you have to project your security if it gets too much for your equipment to handle. (A gun or taser works the same no matter the person who wields it)

If a company is aware of your physical stature, you haven't told any fibs about your skillset and they're willing to hire you as a security guard, then you should be fine.

I can see how having at least some fairly petite women as security might actually be a good move for an employer. It's a generalisation, but women do tend to be better at intuitively reading people and deescalating tense situations. Also, while some big, boozed-up, aggrieved guy confronted with a male security guard might decide that he was going to get physical to demonstrate his masculinity, that same guy would most likely react in a less aggressive way with a small, female security guard.

I'd suggest you might consider visiting the casino and having a chat with the people who work there as security. I suspect you might find that the job doesn't actually involve physically taking down people and tossing them out of the place, but it's more about just keeping an eye out for shady stuff, being a uniformed presence that hopefully deters people from doing said shady stuff and acting as the eyes of the managers. I wouldn't be surprised if most of your interactions with customers were about directing them to the restrooms and other facilities.

If you decide to take the job, one thing you should definitely sort out before your first shift is some comfortable footwear and maybe support hose. Wandering around for hours can be a real killer on your feet and legs.

I worked in border patrol for a while, it was a very physical job and we were expected to handle people who were either very angry, very scared, or very drunk/high/crazy.

I would not hire someone who was small. I’m a large male and there were times where shit didn’t feel worth the risk.

I would tell a majority of my female, and a few of my male, patrols to “just shoot” more often than I did for those who I knew could handle themselves better.

I would not put someone who was small in a position where they had to be physical with people who were already up to no good. And you even questioning it should be enough.
I suggest you quit.

just take fighting lessons or something