In Windows store I’m getting info that DX12 api is required to install the game but I already have DX 12
You need DX12 and a GPU that supports DX11 in hardware. Your Intel HD4000 only supports DX10 in hardware. Get a dedicated GPU like a Geforce GTX 660 to play the game.
Whether or not the HD4000 has the DX11/12 that the game wants, it is much too slow to actually run the game. Per the minimum requirements stated in this article ( News - Forza ) you absolutely must have a dedicated GPU to play this game on PC.