#include <pcre2.h>
int pcre2_set_compile_extra_options(pcre2_compile_context *ccontext, uint32_t extra_options);
This function sets additional option bits for pcre2_compile() that are housed in a compile context. It completely replaces all the bits. The extra options are:
PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES Allow \x{df800} to \x{dfff}
in UTF-8 and UTF-32 modes
PCRE2_EXTRA_ALT_BSUX Extended alternate \u, \U, and \x
handling
PCRE2_EXTRA_BAD_ESCAPE_IS_LITERAL Treat all invalid escapes as
a literal following character
PCRE2_EXTRA_ESCAPED_CR_IS_LF Interpret \r as \n
PCRE2_EXTRA_MATCH_LINE Pattern matches whole lines
PCRE2_EXTRA_MATCH_WORD Pattern matches "words"
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.