Just to be clear, the Leviton is a replacement plug, not an adapter. You don’t plug a wire into the bottom, you wire it through the bottom, and mimimizes extra connections.
That is, you’ll have to remove any existing plug, disassemble the Leviton, wire it, and re-assemble it.
If that’s too scary, and you don’t mind an extra plug and socket in the way consider this 14 gauge extension cord:
They also make pure 90 degree adaptors, but I don't like them. I think it is too easy to disconnect or get a partial connection over time.