It is considered good practice to delete unneeded patches from an ORACLE_HOME in order to save space and reduce the time to install new patches. I made some tests to see the effects of that. More information about the removal of inactive patches can be found in Oracle Doc ID 2942102.1 .
The following steps can be used to setup a Oracle Physical Standby Database managed by Oracle Data Guard Broker. The software versions are: Oracle GI (Oracle Restart) and DB 19.25 and RHEL 8.1. You need to setup both nodes as described here. Afterwards patch it with RU 19.25 as described here. Delete the orcl database on the second node (see here).
This post shows the tcps/ssl setup using orapki for the encryption of database connections. Self signed certificates created by orapki and stored in a Oracle Wallet will be used on the database server and on the client machine. The database server is running Oracle 19.25 on RHEL 8.1. The client machine is running Windows 10.