Do International/Non US Based Users Automatically know/type their county code when filling out phone number forms

I am designing a phone number field for an international audience. Initially I separated the country code with the ability to select ones country from a dropdown. Once a country flag was selected, the country code itself would appear beside the flag, example: +22. The user would then fill in the rest of their phone number.

However, after some discussion with my team, an engineer suggested that most international users already know their country code and should have the ability to automatically start typing it in. Once typed, the default country code would change to the one they've inputted, allowing them to bypass selecting the country code dropdown.

Has anyone had experience with designing phone number forms for international users ? Is it best to separate the selection of the country code from inputting the rest of their number? Does changing ones country code while they are typing undesired UX or do you think it could enhance the experience for international users who may know their country code already?