What 2x2 means
A 2x2 photo is a square photo measuring 2 inches by 2 inches. At print size, that is about 51 by 51 mm. It is common for some passport and visa forms, but it is not universal.
Prepare the original
Use a sharp front-facing photo with your full face visible. Start with more space around your head than you think you need; tight selfies are harder to crop correctly.
Make the file
Choose the requested 2x2 output, crop the face according to the form instructions, and export the file or print sheet. If the form also specifies pixels, file size, or background color, follow those limits too.
Final check
Check the latest official sample for your application. A 2x2 crop can still be rejected if the face size, expression, lighting, or background does not match the authority's rules.