The Basic Plane object (staticMesh) that UE4 offers only has 2 triangles. I am wondering if there is a way to give it more triangles? Can I subdivide it in UE4?
You could try playing around with the Procedural Mesh Component (which is flagged as experimental).
If it were me though I’d just import a more subdivided plane mesh from elsewhere.
Depends on how are you going to use this triangles if with materials read about tesselation.
Otherwise launch blender and make plane divided like you want.
Delete default cube Click add > Mesh > Plane then click it with right click than press tab than press w and click subdivide. Then you will also need to generate UV so click u and click smart UV project than export as FBX.
(If it’s not avaiable than you need to go to File > User preferences > Addons and search for fbx and enable.)
Looks complicated but blender is easy.