I'm running Monterey and have the feature, but it's only inside Preview, which means I need to either open the image in Preview or take a screenshot and then open a new image in Preview to paste the screenshot, before getting the text
Check out Textinator [0] which is an open source macOS app that watches for screenshots and automatically does text detection then copies text to clipboard. (Disclaimer: I'm the author). It works on macOS 10.15+