Apologies for the delay in responding to this post. As I understand you want to extend SAML token validity for your application.
Refer to this article https://learn.microsoft.com/en-us/azure/active-directory/develop/configure-token-lifetimes#create-a-policy-for-web-sign-in:~:text=Create%20a%20token%20lifetime%20policy. which has the steps on how to increase the Tokenlifetimepolicy for your application.
Let me know if you have any further questions.