Create a new scene with StaticBody3D as root
Add MeshInstance3D and CollisionShape3D
It is a physics node designed for non-moving objects like floors, walls, or static scenery. It is immovable by external forces (rigid bodies) but can move via scripts or animation, without affecting other bodies in its path. It requires a CollisionShape3D child to function.
Select the MeshInstance3D
Set the Mesh property to PlaneMesh
Add a new StandardMaterial3D
Change the Albedo to a colour like blue
Add the floor to collision layer 4 (floor)
Set the floor to look for Mask layer1 (player)
Save the scene as floor.tscn