To continue the HxH manga after the anime, check manga subscription platforms or visit your local comic store. They should have the volumes you need to pick up where the anime left off. Also, some online manga reading sites might have it available.
The Hxh anime ends at a specific point in the manga that's determined by the production decisions. It's not a straightforward mapping, but you can find out by comparing the storylines.
From what I can assume, if it's like other similar works, it may have a unique power system. For example, characters might possess special abilities or powers that are related to their identity in the school or the world they are in. This could lead to battles or competitions among the characters, which is a common and exciting element in such stories.