Both about a new topic or a topic that you already are interested in.
There are TIL communities here on lemmy and they are good, but mostly not about using the info to do things.
Any websites, rss feeds, youtube channels, lemmy(or other site) communities etc. that you subscribe to for that?
And going beyond online stuff, any books or publications or groups that you like?
Web forums are pretty interest specific, so the ones I lurk around might not appeal. XDA forums for android modding, VOGONS for retro computer sound, gbatemp for console modding, segaxtreme for sega game hacks and fan translations, shmups.system11 for discussion about shoot’em’up games as well as analogue gaming hardware. That’s a few of the boards I read through. Wikipedia is good for learning something new, and then finding a web forum on the topics that catch your interest is good for building on that. Interest specific subreddits are okay as well. Lemmy, not so much at the moment.