@renatozechetto
As long as you cw it properly an 18+ image isn't that bad :) Provided, of course, that the comic is 18+. For reach; use hashtags - since people can follow them and the feed is chronological they have punch. 3 - 5 is a good amount. Boost your comic toots often too.
Another thing you can do is talk with people who shares your interests. It's a bit hard to get out of the stand-up version of social media that is fb/X/etc, but it's rewarding in the long run.