No. You cannot use a threaded fork with a threadless headset. Back in the day, riders would grind the threads off shimano headsets to use them with threadless setups, but you cannot go the other way
You can get a threaded headset and stem but I would just get the right fork. And I wouldnt go rim brakes from discs. If anything, I would go hydro over cable
700c, 1 1/8" threadless, disc, suspension adjusted P2 is what you want. Does your current wheelset have rim braking tracks?