"Bake Lightmaps (light maps) in Blender (https://www.katsbits.com/codex/bake-lightmaps/)" - https://www.katsbits.com/codex/bake-lightmaps/ taking a pretty detailed look at using the Blender 3D's internal Bake system to generate lightmaps for single or multiple objects - no plugins, addons used, just default Texture Bake.