In Wolcen: Lords of Mayhem, you can customize your equipment by adding several colors and choosing a different model for each weapon and weapon type. This tutorial explains everything about customization.
To unlock new models of your equipment, you simply need to collect weapons and weapons by opening chests or removing enemies (image1et2).
As for models, you will always find a dye by eliminating enemies or by opening chests (image3et4). Use these tinctures from your inventory to open them.
Now that you have the models and dye, press the default key "B" to open the cosmetic inventory (image5). Select the equipment you want to change by clicking the icon on the right (image6).
Then select the model you want by selecting the model on the left (image7). Then go to the dye, select the color area, and select the colors you want (image8). Finally press accept to confirm your selection. Note that cosmetic conversion costs gold.