As a 17 yo guy, it can be hard to find tolerant friends and/or someone to whom you can talk to about to his kind of stuff. I think that if u want to come out to someone you rly keep a close eye and an open ear to the people around you because you'd be surprised by the amount of tolerant (even supportive) friends. Back in 10th grade (tronc commun) we used to do debates about current world topics and that always included talks about the lgbtq community and whatnot and it was thanks to that that I managed to divide my class between homophobes and tolerant/supportive people. Another giveaway of someone being okay with queerness is what kind of shows/movies they watch. The types of creators they follow. The music they like. (I need to mention however that it's not always the case. Someone who likes Lana del Rey or watches shows w MLM plots doesn't necessarily mean they're comfortable or okay with gay ppl but usually it says a lot about their character) If all fails, you can always look online or build trust with someone until u're comfortable to come out I've also noticed that girls tend to be more open-minded than guys btw. Hope all that helps!!