Well let's math it out. There are 15 limited male 5*s in the game right now. Average rolls to get a limited 5* is 104. You get about 75 rolls on average each patch, so 9 patches per year = 675 rolls or close to 7 limited 5*s per year.
The permanent content in the game (exploring the world, quests, etc) gives a huge starting amount, at the start of Inazuma someone counted like 200+ rolls from permanent content, with Sumeru and fontaine now I bet that number is closer to 500, so that's 5 5*s right off the bat too. So you can get 12 out of the existing 15 male 5*s in your first year playing genshin if you roll for only 1 copy of each and don't roll for girls or weapons.
They also release new male 5*s from time to time, 2021 had 3, 2022 had 3, 2023 had 5, let's average it to 4 a year. So at the end of the first year you'll be at 12/15 which is most of the way there, and at the end of the second year you'll be at 19/19. So, two years tops with average luck, completely f2p, if you want absolutely every single male character. Tons of 4* boys too but not counting those since you'd get them naturally along the way, and the two non-limited 5* boys you'd also get at some point during this time.