I’ve looked and looked at tutorials, but none of them seem to have the same kind of functions as my version of Harmony Essentials. Is it at all possible for me to use painterly brushes on my current software, or no? If it is possible, how can I make that happen?
Essentials does not include texture brushes or bitmap drawing/painting tools.
https://www.toonboom.com/products/harmony/features
If you want a painterly effect you can use another program (a Photoshop, Painter, Manga, etc.) to create the art, then export it, then import it into Harmony and animate using a frame by frame process.