For me it depends on the character. For some of my magically enhanced characters/Force sensitives... Definitely a small army or two.
I have a Sith Juggernaut character who would literally keep fighting till she dropped dead and take no notice of the fact that she was almost disembowled, while her wife is having an aneurysm in the background and screaming "WOULD YOU PLS STOP FOR FIVE MINUTES JFC!!" and trying to make sure she doesn't die, for example xD

Whereas some more of my "normal" / non powered characters would realistically start to feel overwhelmed by about 6 or more at once, but could take sniper or pot shots out of cover at several people

And equally, I have medics or chars who are otherwise not combat savvy who would probably as good as drop dead if you breathed on them too heavily XD

Ohhhhh man, definitely a fair mixture. I've maybe written one or two characters who would absolutely wreck a crowd of people and a couple who are worthless without a weapon, but I normally make my characters at least competent in a fight. Most of them are capable of taking on at least one person at a time. Sometimes more depending on the type of RP. It's typically very dependent on what type of RP it is.