What android OS do you use? On stock Android 14 (GrapheneOS, but it's not a GOS feature) this functionality is built into the stock screenshot tool.
pwr+voldown -> tap screenshot that appears in the overlay after you take it -> tap the crop tool . I suppose step three could be removed but what if you want to do something that isn't cropping? There are lots of other features so at some point you have to tell the tool what you want to do.
No, I don't have markup installed (it is there in apps but not installed from the mirror).
I think in my case the screenshot functionality is built into AOSP and the editor you get when tapping the resulting preview overlay in the lower left corner of the screen is part of the "gallery" app since using the "edit" feature from gallery launches the same editor. Maybe GrapheneOS just sets that as the default editor, I'm not sure.
AOSP gallery that comes with GrapheneOS. The app info says it's called com.android.gallery3d. There's some info here in the docs about the relationship between camera, edit functions, and the gallery app.