You don't get any practice. That's the problem. Online dating is a distinctly different game from dating. And the problem is that sooner or later it will have to turn into actual dating. But you are being filtered through an unreasonable and non-working filter.
If you want practice and opportunities, go out and and try yourself in bars/clubs. I know it sounds scary and and even superficial but it's humane and it does work. I know, I've been there. My social circle never worked for this purpose, especially not after high school. I've tried online dating about a decade ago just to find that it's completely dysfunctional (it was, even back then!).
However, talking to actual people in bars was always fun even if scary at first (I like that environment a lot, so that might be a factor too, others may work for other people). Heck, even a rejection feels real and less upsetting than online. Not to mention that even the rejections are waaay more civilized and a lot less likely. I used to keep thinking about how to fix online dating back then and one of the problems is that socially unacceptable behaviour is not only goes without negative consequences there but it's actually the easy thing to do. Thus no surprise the whole thing ends up being toxic pretty quickly as people constantly annoy and provoke each other through this.
E.g. if you start to talk to someone in a bar, even if you say the most boring thing possible, they will almost never just turn their back on you and don't respond. Even a quick rejection will probably include a smile and a response like "no, thanks", or "I'm with my friends", etc. But, at least in my experience and my case, that would be below 10% and the other 90% would be at least a short conversation. Which just feels good. Compare this with what you get online. (In my case it was, again 10 years ago!, the reverse or even worse. I.e. over 90% no response. Same person, same looks.)
I have a friend who is very good looking (and I mean it: girls turn around after him in the bars or straight walk up to him) and even he doesn't have too much success online. I mean he does get matches, probably a lot more than e.g. I would get, but then he usually runs into dates not working out, girls looking vastly different than on the profile picture, etc. This just doesn't happen IRL.