PCRE2 is a re-working of the original PCRE (Perl-compatible regular
expression) library to provide an entirely new API.
PCRE2 is written in C, and it has its own API.
There are three sets of functions, one for the 8-bit library, which processes strings of bytes, one for the 16-bit library, which processes strings of 16-bit values, and one for the 32-bit library, which processes strings of 32-bit values.
There are no C++ wrappers. The distribution does contain a set of C wrapper functions for the 8-bit library that are based on the POSIX regular expression API (see the pcre2posix man page).
These can be found in a library called libpcre2posix.
Note that this just provides a POSIX calling interface to PCRE2; the regular expressions themselves still follow Perl syntax and semantics.
The POSIX API is restricted, and does not give full access to all of PCRE2's facilities.