Depends on what type of graphic design you want to learn. I've been in the game a really long time and there are many facets of graphic design. You have to first tell us, what type of graphic design do you want to do? Product packaging, like all the stuff you see on store shelves? Movie posters? Movie matte painting? Graphic novels? Magazine layout? Corporate identity and brochures? I could give different answers for your question, depending on what area you want to learn.
If you just want to learn graphic design programs
https://www.lynda.com/
If you want to learn about the principals of design, many places + books
https://blog.prototypr.io/10-basic-principles-of-visual-design-55b86b9f7241
If you want to learn about design for Hollywood
https://www.thegnomonworkshop.com/
If you want to design ...
Magazine, multipage brochures, catalogs - InDesign
Small brochures, posters, logos and identity systems - Illustrator
Matte painting, graphic novels, movie posters, photo manipulation - Photoshop, Lightroom, and Painter