High Level Steps:
==============
RMAN - Database backup:
rman target /
CONFIGURE CONTROLFILE AUTOBACKUP ON;
RMAN] backup database plus archivelog;
RMAN] backup database format='/u01/backup/backup_%d_%T_%U';
RMAN] backup archivelog all format='/u01/backup/archive_%d_%T_%U';
RMAN] list backup of tablespace system;

SQL] shut immediate
SQL] shut abort;
SQL] startup mount;

RMAN] restore datafile 1;
$ls -ld system*
SQL] select file#,checkpoint_change#, status, recover from v$datafile_header;
RMAN] recover datafile 1;
SQL] select checkpoint_change#, status, recover FROM v$datafile_header;
SQL] alter database open;

Please refer the below blog for more details:
https://mallik034.blogspot.com/2022/01/rman-recovery-scenario-system-datafile.html

Regards,
Mallikarjun Ramadurg
Mobile: +91 9880616848
WhatsApp: +91 9880616848