How to get an image of the right size in Wordpress?

Question

WordPress

The task is this. Images of completely different sizes are inserted into the post, that is, large, medium, etc.
I need to get links to images and change them to my custom-size from function.php.
Previously, I did this: I changed all the pictures to 150x150, and then, depending on the needs, I substituted another ending like "-1920x1080.jpg". But all good things come to an end quickly and this crutch is no longer relevant, images with a free height were required.
The question is how do I match the pictures from the posts with my required size?

Answer 1

So far, the best idea is to search by part of the name in the folder for a suitable picture, but is there really nothing built into the VI in this regard?...