foreword
sketchfab.com is a good website from which you can download many free models, usually in fbx format, but you may often encounter the problem of incorrect model materials when importing models.
Option One
selected model
Modify the material location setting to Legacy
It will generate materials based on the textures that come with the model
Change the transparency of the material to 1
Option II
First drag the model into the scene, you can see that the model is gray at this time, this gray Shader should be automatically generated by Unity
see the catalog of models
Select a colored map and drag it to the model
Add Mesh Collider
The fbx model does not have a collision body, so there will be a situation in which the mold is worn.
If desired, a Mesh Collider can be added to the model and all of its sub-objects, so that it doesn't wear out.
