bunch of textures and sprites here:
https://opengameart.org/content/25d-fps
https://little-martian.itch.io/retro-sprite-pack
https://little-martian.itch.io/retro-texture-pack
use https://www.advancedrenamer.com/ to easily rename the textures so they only have letters and numbers in the filename. NO special characters, no spaces, no _underscores_ just a to z and 0 to 9
your on your own for models. i wouldnt suggest even messing with 3d models for your first game with efpse.