Gimp is not the tool. It is a 2D bitmap editor. You cannot generate a mesh to deform and map that to an image.
Any 'depth' in Gimp is created by applying light and shadow as in any 2D painting. One way is using a bump map: example https://i.imgur.com/6EiXWl3.jpg
For freeware (Just looked up 3DS Max - £234 a month - A*t*desk what a bunch of cr**ks))You should investigate Blender https://www.blender.org/
Since you are using linux there is an appimage here: https://www.blendernation.com/2020/08/19...-released/ might be good for a try-out
Any 'depth' in Gimp is created by applying light and shadow as in any 2D painting. One way is using a bump map: example https://i.imgur.com/6EiXWl3.jpg
For freeware (Just looked up 3DS Max - £234 a month - A*t*desk what a bunch of cr**ks))You should investigate Blender https://www.blender.org/
Since you are using linux there is an appimage here: https://www.blendernation.com/2020/08/19...-released/ might be good for a try-out