You can do that by
1) Create a custom custom field setting https://www.advancedcustomfields.com/resources/adding-custom-settings-fields/ that uses a radio field, you’ll probably need to get the existing image sizes, don’t know how to do that off the top of my head.
2) Creating an acf/format_value filter https://www.advancedcustomfields.com/resources/acf-format_value/ that returns the URL based on the custom setting.
