Regular expressions cannot be used as parameters in the standard Oracle built-in text search functions: LIKE, SUBSTR, INSTR, and REPLACE.
Regular expressions have their own versions of the same functions: REGEXP_ LIKE, REGEXP_SUBSTR, REGEXP_INSTR, and REGEXP_REPLACE.
SQL> declare
2 v1_tx VARCHAR2(2000):='*ABC*BBC*';
3 begin
4 DBMS_OUTPUT.put_line('First hit:'|| REGEXP_INSTR(V1_TX,'A|BBC',1,1));
5 DBMS_OUTPUT.put_line('Second hit:'|| REGEXP_INSTR(V1_TX,'A|BBC',1,2));
6 end;
7 /
First hit:2
Second hit:6
PL/SQL procedure successfully completed.
SQL>