can I provide one image with high resolution for all screens?
and then give it a width with a relative unit like rem and allow the browser resize the image itself
I use this to enhance the speed with screens max 480px. The “correct” resolution for each media. Using the same high res image for all screens may affect the speed.
If you are very good at optimising your images and don’t go overboard with massive images at massive quality then you may indeed select a mid-range quality and size image that will suit larger or smaller displays.
It won’t be as good as swapping the image but it may be good enough unless this is a site devoted to images where you need the highest quality. It’s all about compromise
Whatever you do you should more or less always be making them responsive to their environment anyway and not fixed sizes.