These options are indeed available in project settings, but the game engine doesn't support versions older than Directx11:
If your graphics card doesn't support DirectX11, unfortunately, I don't think it's possible to launch the game.
EDIT: The game currently supports DirectX12, so if your graphics card is compatible with DirectX11 versions but not with the DirectX12 version, I understand that this may trigger this error.
If you wish, I can release the game with DirectX11 support if that helps.