#include <pcre2.h>
int pcre2_set_character_tables(pcre2_compile_context *ccontext, const uint8_t *tables);
This function sets a pointer to custom character tables within a compile context. The second argument must point to a set of PCRE2 character tables or be NULL to request the default tables. The result is always zero. Character tables can be created by calling pcre2_maketables() or by running the pcre2_dftables maintenance command in binary mode (see the pcre2build documentation).
There is a complete description of the PCRE2 native API in the pcre2api page and a description of the POSIX API in the pcre2posix page.