2021-06-10T04:00:00Z I want to know how to create a variable size grid that I can overlay on images. I understand layers, but cannot find any method for creating the grid.
If I understand, you want a grid that is part of painting (in a layer)?
Or you just want a grid as an assistant tool?
For a grid that forms part of the image, GIMP has a grid maker in Filters → Render → Pattern → Grid.
Some time ago, I made a DIY Grid Maker tool that’s crude and simple but it works and you can read about it and get it from here (instructions and explanations included):
If you want some kind of overlay assistant for guidance (that’s not part of the final image), you can use the Grids and Guides docker that can be enabled from Settings → Dockers → Grids and Guides.