UV Unwrap and Diffuse Texture (Palette):

As these models are made with a low poly style, a single texture with an array of different colours has been used. The Unwrap is straight forward and simply the model faces are placed over different colours in the palette. Technically no texture is needed at all, and built in base colours (in your 3D Program) can be used. Although using a texture means just one material is required for the entire collection and also it maintains consistency across different 3D programs. (E.g. Blender to Unreal Engine).

A lower resolution texture could be used, but staying with slightly higher resolutions does mean that colour blending can be used as well in the colour palette (if edited in a paint program). Also it’s easy to create new colour palette textures and swap them around if looking for a different look.

Diffuse Texture Palette with UV unwrap:

(Please note this doesn’t come with a Normal texture, as no depth or addtional details were added via a normal.)