assuming you have the control FILE and

after a “startup mount;”

using the controlfile to restore/RECOVERABLE

rman target /
restore database UNTIL TIME
“to_date(’12/31/2021 11:34:50 am’,’mm/dd/yyyy hh:mi:ss am’)”;

recover database UNTIL TIME
“to_date(’12/31/2021 11:34:50 am’,’mm/dd/yyyy hh:mi:ss am’)”;

alter database open resetlogs;

OR

run
{
set UNTIL TIME “to_date(’12/31/2021 11:34:50 am’,’mm/dd/yyyy hh:mi:ss am’)”;
restore database;
recover database;
alter database open resetlogs;
}