I would like to know how to work with layers in photoshop

​@GoldenLover your post title mentions layers, however, the body text just mentions image.

It can depend on whether you wish to resize the entire image (canvas + layer/s) or resize just a layer without affecting the canvas size.

Other things to consider are whether you’re upscaling or downsizing, image content and how different resampling/interpolation algorithms affect the results.