I have a large environment that the TZs between hosts & Splunk are off by minutes & hours at times. How do I get started ? If you have done such a project please share the procedures - any helpful SPLs. Thanks a million.
As I already told you - it's out of the scope of splunk administration itself. In a properly maintained infrastructure you use a common time source (usually a NTP sever(s)) to which other components sync.
Then it's up to event source systems to either configure logging with common timezone (preferably GMT) and/or make the source include the TZ info in timestamps.
If it's not possible it's up to the splunk admin to configure apropriate TZ offset on for particular inputs/sources/sourcetypes.
Nothing automatic here.
As I already wrote you, you can check the difference between the time reported in the event and the time it was indexed but that's it.
My suggestion would be to manually edit the props.conf for your hosts to set the TZ.
Please see check this link for an example and TZ attributes: https://docs.splunk.com/Documentation/Splunk/8.2.2/Data/Applytimezoneoffsetstotimestamps
Another option would be to set up an NTP server and point all hosts and Splunk servers to that server.