How to mark an existing SQL Plan baseline as fixed

Thanks a lot to Tim Hall for providing this simple example:

SET SERVEROUTPUT ON
DECLARE
  l_plans_altered  PLS_INTEGER;
BEGIN
  l_plans_altered := DBMS_SPM.alter_sql_plan_baseline(
    sql_handle      => 'SQL_7ff180a4583f257d',
    plan_name       => 'SQL_PLAN_7zwc0njc3y9bx2c993bf4',
    attribute_name  => 'fixed',
    attribute_value => 'YES');

  DBMS_OUTPUT.put_line('Plans Altered: ' || l_plans_altered);
END;
/

The details for the plan baselines can be found like this:

SELECT sql_handle,plan_name,origin,enabled,accepted,fixed
FROM dba_sql_plan_baselines
WHERE plan_name ='SQL_PLAN_7zwc0njc3y9bx2c993bf4';

Result:

SQL_HANDLE	PLAN_NAME	ORIGIN	ENABLED	ACCEPTED	FIXED
SQL_7ff180a4583f257d	SQL_PLAN_7zwc0njc3y9bx2c993bf4	AUTO-CAPTURE	YES	YES	YES

After fixing the plan, all the plan alternatives for the SQL ID can be seen below:

SELECT TO_CHAR(LAST_ACTIVE_TIME, 'dd.mm.yyyy hh24:mi') "last active",
       SQL_ID,
       PLAN_HASH_VALUE,
       SQL_PLAN_BASELINE "BASELINE", 
       SQL_PROFILE,
       IS_RESOLVED_ADAPTIVE_PLAN,
       CHILD_NUMBER AS "Child Num",
       ELAPSED_TIME,
       EXECUTIONS,
       ROUND(ELAPSED_TIME/1000000) "duration (sec)"
       ,CASE WHEN EXECUTIONS > 0 THEN
        ROUND( (ELAPSED_TIME/EXECUTIONS)/1000000, 1)
        ELSE
            NULL
       END "sec per exe"
FROM V$SQL 
WHERE SQL_ID in('2mympbsn3r4rk')
ORDER BY sql_id,LAST_ACTIVE_TIME DESC;

Result:

last active	SQL_ID	PLAN_HASH_VALUE	BASELINE	SQL_PROFILE	IS_RESOLVED_ADAPTIVE_PLAN	Child Num	ELAPSED_TIME	EXECUTIONS	duration (sec)	sec per exe
04.12.2020 09:49	2mympbsn3r4rk	480132689	SQL_PLAN_7zwc0njc3y9bx3bf43977			1	612838711	116	613	5,3
04.12.2020 09:49	2mympbsn3r4rk	3102497174	SQL_PLAN_7zwc0njc3y9bx2c993bf4		Y	2	203961	191	0	0
04.12.2020 08:49	2mympbsn3r4rk	480132689	SQL_PLAN_7zwc0njc3y9bx3bf43977			0	2247452482	30	2247	74,9