Convert *.FBX to Solid for Physics Sim I have downloaded a .fbx model from mixamo and import into Blender 2.80 beta without issues. 

However, I want to perform a physics sim with that model by draping a cloth over the model and unvealing it. However, there is no option for me to set the .fbx model as a rigid body or collision target. 

Do I need to convert the .fbx model into a mesh or solid? If so, how can I do it?

Thanks.
The FBX should presumably include a mesh when it is imported. Most likely if it came from Mixamo it also includes an armature, and the mesh will be parented to that armature.

Make sure you select the mesh, not the armature, and then you should be able to add physics properties to the mesh. 

In this case you want to go to the Physics tab of the properties editor and add collision to the object. This will tell any cloth objects that this object should be treated as an obstacle.