I got the answer for this - actually this is by design:
The nginx service[0] in RHEL/CentOS 8 uses PrivateTmp=true directive so it doesn't see the /tmp/nginx directory you just created. You could either add a service dropin with ExecStartPre= which will do the log directory setup or drop PrivateTmp=true to make this work.
The nginx service[0] in RHEL/CentOS 8 uses PrivateTmp=true directive so it doesn't see the /tmp/nginx directory you just created. You could either add a service dropin with ExecStartPre= which will do the log directory setup or drop PrivateTmp=true to make this work.