Are there any other processes that kind of do what photosynthesis does?

yes it can change the leaf color or it could take in light aka plant sunbathing.

Explanation: i just know about plants

Yes there is. It's called chemosynthesis

Explanation:

In some deep ocean places, groups of living species (excluding bacteria) have been discovered that rely exclusively on chemosynthetic bacteria, with a full food chain beginning with these chemosynthetic bacteria as primary producers.

And photosynthesis is evidently not possible at the depths where these organisms have been discovered (4 km and deeper)