You can check out this thread from the other day.
Also “easy” manga tends to have less furigana because the publishers kind of assume you should know how to read all the kanji in them.
Oftentimes, for all published things, there will be furigana every once in a while if a funky word pops up or if it has a different reading than normal. And books/novels tend to have less furigana but obviously the reading level is much higher. You could try picking up some kids’ books though.