Alright, I've been at this for almost half a decade and we're about the same age, so I'm gonna take you on a journey of Hard Reality here. And I do it with love.
99.9% of 18-21 year olds are in no way, shape, or form prepared to cam. Period. Let me emphasize again: period.
Why? Well, realistically, how much life experience does she have? And I don't mean to demean her or you by calling her naive. She could be incredibly mature for her age, but she has only recently graduated high school, is unlikely to have been to college for long if at all, unlikely to have lived alone if at all, unlikely to have been responsible for bills, etc. So, basic Adulting 101 is still a new skill set to her. Hell, it was a 'new' skill set to me until I was about 23, and I was considered one of those super mature 18 year olds with my shit together.
And besides life experience, how much sexual experience does she have? Camming is not for the faint of heart. It's going to be a lot of men treating her like a fuck hole, to be blunt. She'll be screamed at, demeaned, insulted, and jerked around. On the best of days, she'll be bringing pleasure to other men for money, in ways she may not always be 100% comfortable with. We can sugar coat it all we want, but every sex worker has to come to grips with the fact that their job involves a degree of objectification and being placed on a pedestal. It means taking something that society has taught us is personal, sacred, and not to be shared, then monitizing the shit out of it. Even if you're there to hold her hand, that sits with a person. Going into sex work without a firm grasp of your own identity, both personality wise and sexuality wise, is a recipe for disaster because she almost definitely doesn't know herself well enough to separate what happens at work from her own, still-forming, view of sexuality, self, and the world.
This job impacts world view. You stop looking at people with rose-tinted glasses and see all the disgusting bullshit they can pull. Sometimes it's good, but other times it makes you distrustful and less able to engage with people. You know how cops see the very worst of society and you can just tell that it impacts them? Sex work is no different.
On top of all of that, there's the present and future impact on her 'real life' that it would have. What is she going to tell her friends? Her family? Will she work another job, or fumble trying to explain her employment gap after spending months/years doing sex work she can't put on a resume? Know now that if she goes into sex work with you, the door is superglued shut to teaching, any work with children or vulnerable populations, religious organizations, and so forth. Even if her future career doesn't ask, they can fire her without explanation for it. I had a friend who stripped several states over through college, then got outed 5 years later when she was a floor nurse; she lost her license because the board saw it as 'unprofessional conduct' and a 'reflection of poor character.' What will you do for her when (NOT IF!) word gets out and people, inevitably, shame her, demean her, and shun her publicly? Best case scenario, she has to live with lying; worst case scenario, she's permanently and royally screwed. Neither are fun.
And what about strangers? How about if some crazed fan finds out her name and info and comes after her? Yeah, that shit happens with alarming frequency, and even the most vigilant can't do much. Don't think it could happen? You've already given me your age, her birthdate and age, and photos to go off of--on a very public, highly-ranked forum that is the top of every google search. Information slips out of even the most careful workers. Whackos are happy to take full advantage.
And what about you? How will you respond to the inevitable accusations lobbed against you when it gets out? Again, when, because it ALWAYS GETS OUT. You're 10 years her senior. Her family, her friends, and maybe even yours will look at you with a deep sense of mistrust, at best. At worst, they'll accuse you of manipulation, abuse, and grooming a barely-legal young girl. Don't kid yourself.
Moreover, why do you want to cam together? For extra cash? Because it's sexy? People will ask WHEN they find out, and those answers will sound flimsy at best. You'd better have a rock solid reason, that she 100% agrees with, or you're asking to be flayed alive by an angry crowd.
She's been 18 since this summer and you met her afterwards? Your relationship is brand new. You're older, and cooler, and she probably looks up to you and desperately wants to please you. She'll probably do things outside of her comfort zone hoping to make you happy. On top of it, she almost certainly has no idea of the potential consequences of getting into this job. Take a good few minutes--right now--to consider how much that's impacting her 'yes' to camming with you as a couple.
You cool with all those implications and potential issues? I wouldn't be, personally, and you seem like a reasonable dude so far, so I don't know that you would be either.
I really could go on, and on, and on. I won't. Hopefully this giant wall of text gets the gears turning enough for you to realize that sex work means every worst case scenario is now a plausible reality. Is the potential extra cash worth it? So you make a few hundred and she hates it; all of the above still applies. You make a steady income? Still applies. You end up the 1% of 1% of 1% who make it big? Still applies. It's a lot of risk for a low possibility of reward.
Bottom Line -- you may have what it takes, but I highly doubt she does. So to answer your thread title directly - NO!