Crop and Lock, available for both Windows 11 and Windows 10 v2004 (19041) or newer, has two modes — a non-interactive Thumbnail crop that’s essentially a live feed of the area you select that updates with the page, and a “Reparent” mode that Microsoft writes is more interactive, but could have compatibility issues with some apps.
You’ll need to make sure the window you want to crop is selected before you enter the shortcut — you can’t just grab any old app window on your screen.