Not impossible, but probably easier to use perspective camera. If you use orthographic camera then you’ll have to add more movement logic on your own instead of just placing walls and boundaries and letting the character move in true 3D. But sure you can do that.
If you want to do it without true 3D movement laterally in 4 directions you will be better off probably not using Character Movement but use a basic Pawn instead, with a basic Controller that you can program only the movements you want, and instead of using gravity, you will manage all the vertical movement yourself using timelines or Tick, and make it actual Z axis movement just without the built in gravity. OR you can do like you illustrated and make it lay on the ground instead, and point the camera down to look like it is standing up. You can really do whatever you want. Just some things are harder than others and don’t have built-in ways in Unreal - you have to program it all yourself for some ways.