Dont think you can do this with the normal software. But like Korth said there might be some software that i smade for downscaling a monitor. But this is software and really dont think you will gain more fps! The black pixels still need to be refreashed as well by your GPU. So only a hard option would alow this for you to get more more FPS.
Aslo the 1050ti oc is already oc'd from the factory. I OC'd lots of cards just because I could. Best result where always from AMD card... but that another subject.
Just doing some fast numbers.
Lets say you have 60 FPS now.
You get a plus 5 to 8% stable overclock. Lets say 8% you gain 4.8 fps.. i
That is in theory... moslylike you you will gain less IRL gaming.
TBH.. a 1050ti is not suitble for a 1440P screen when you demand high FPS.
I have 980ti and I there lots of games that i cannot play on ultra settings. Even with my overclock 26% of default. ( and this comes factory OC'd on 22% )and is custome watercoled as well.
Just saying what you want is not really going to workout at all.
Hopefully you will find a solution. Would like to know if you found 1.. Maybe I can set my PUGB on 1080p
GL HF
Try more, Try harder, Try and previal