Talking to girls online

I am pretty acoustic guy 19 years old, not in a bad way because I have pretty good social skills irl, I can talk to women and men with no problem, and I like girls. But when it comes to messaging girls I can’t feel the room. How do I slide into a girls dm, what should I say without sounding creepy?

I’m single and want to date women but on dating apps I feel like it’s mostly about sex and the same when I go home with a girl from a night out. It’s always sex, take her IG and then she ghosts me:(
My friends say I’m lucky because I get women and get laid but I don’t feel lucky, Im a relationship guy.

I’m 19 so i understand every girl don’t want a relationship, most of my friends who are in relationships start of as friends, but I don’t like that at all, I pretty much friends zone a girl I’m friend with and can’t think of her like girlfriend material when we become bros haha. I like to start of with a girl not as friends I want to know from the start that we have interest for eachother.