External

Free programs I use often and highly recommend

Krita

https://krita.org/en/

App for digital drawing

Blender

https://www.blender.org/

3D modelling + animation and a lot more features that far exceed what a human can learn in their lifetime. Not very intuitive, so be prepared to watch some tutorials before diving in

Godot

https://godotengine.org/

Game engine which is evolving at a rapid pace

Kdenlive

https://kdenlive.org/

Video editor from the same organization as Krita

KiraStudio

https://kirastudio.org/

Audio workstation focused on simplicity