Unless you've changed chrony's configuration, you don't need to do anything but start the service.
systemctl enable --now chronyd.service
The default configuration automatically steps the clock at startup (using the makestep
directive) if it is more than one second different than the default NTP servers.
If you explicitly removed makestep
from the configuration, you can step the clock by using the command
chronyc makestep
You should NOT do this if you used the non-default rtcfile
option though, as it will cause the RTC drift to be recorded incorrectly.
For further details see the RHEL 7 chrony documentation.