Is there a common regular expression that replaces all known special characters in non-English languages:
é, ô, ç, etc.
with English characters:
e, o, c, etc.
No, there is no such regex. Note that with a regex you "describe" a specific piece of text.
A certain regex implementation might provide the possibility to do replacements using regex, but these replacements are usually only performed by a single replacement: not replace a with a' and b with b' etc.
Perhaps the language you're working with has a method in its API to perform this kind of replacements, but it won't be using regex.