How to programmatically reduce the screen size?

Question

Monitors

Hello.
I want to buy a monitor with an aspect ratio of 21:9 and a resolution of 2560 × 1080. Unfortunately, few games adequately support such parameters.
Is it possible to adjust the display area to the current resolution? For example, when running a game at 1024 x 768, that number of pixels should work in the center of the screen, with the corresponding black bars on the top, bottom, and sides. The resolution settings inside the game are not suitable, as they try to stretch the image as much as possible, without creating black bars at the top and bottom, and also cropping part of the image. GTX 1080
graphics card .

Answer 1

NVIDIA Control Panel

Works in games too.