ACF doesn’t check the URLs to see if they are real, it just check them to see if they either contain ‘://’ or start with ‘//’, so you can put anything in there that looks like a url like http://thisdomaindoesnotexist.com/
If you mean you need to override the checking and allow content that does not look like a link then, it might be possible. You would need to remove the filters that acf add, and that could be difficult.
This is a guess, so it might not work. The guess is the first part of the array, figuring that out is where you might have a problem that that’s my best guess at it.
remove_filter('acf/validate_value/type=url', array(acf()->fields, 'validate_value'), 10,);
