Hi Rashmeet,
It is possible when you use EnforceRealmTimeouts .
To override the Idle Timeout value,
Create Authentication event RULE with action OnAuthAccept
Create response of type WebAgent-OnAuthAccept-Session-Idle-Timeout, and set to the desired value in seconds.
In the Policy add the Authentication event RULE then set the set the new responses to that rule
Please check below link.
How to Enforce Timeouts across Multiple Realms
Thanks,
Shankar