You need to edit "../../ECM/WEB-INF/web.xml" file and below is the tag wherein session timeout can be configured.
Note that the value of the timeout is set in minutes, not in seconds.
Hope this will be applicable for the environment where the SSO is enabled using okta. Also when we are trying to acces the "../../ECM/WEB-INF/web.xml" we are gettng page not found. Can you let us know where to locate this page in Saviynt.