What is the correct way to add special materials in this application.

[Oleksandr-Fedorov]

In short, I noticed that some models, for example, downloaded from Sketchfab can display textures only when you modify them a bit in blender by setting Viewport Shading and after exporting the model, but in this application textures are displayed automatically without any intermediate steps.
If it is possible, please, I want to know how it can be done.