This is also built in to macOS and iOS now too. Such a handy feature that I find myself using a lot.
I don't THINK there is a way to do it straight from the snipping tool, but someone correct me if I'm wrong.
Edit: Personally I use the paid Cleanshot app, which is not only great for OCR but all sorts of screenshots, videos, and annotations: https://cleanshot.com/ You just drag a box around the text, click "OCR", and it gets copied into your clipboard. I find it easier & faster than having to deal with Preview.
I think the free Shottr does the same: https://shottr.cc/
It can be done from the screenshot tool. Take the screenshot, and an icon will appear in the lower-right corner of the preview. Click that icon and it selects all of the text in the preview.
If you don't want all to select all of the text in the window, just select the text in the image the same way you'd select text in any other program.
I find it easier & faster than having to deal with Preview.
OCR is system-wide on macOS without Preview.
On recent Macs, it's automatic in most programs, including Mail, Preview, Quickview, and others. Just hover your pointer over text in an image, and if the computer recognizes it, you get a text cursor so you can select the text. No extra software needed.
If it's a language you can't read, you can often ⌥click the selected text and it will be translated into the language of your choice.