Create a policy
Login to Microsoft Graph
Make sure to set consent for Policy Read and Write Application Configuration.

- Use the Get to check if any policy exists in the environment.
Get: https://graph.microsoft.com/v1.0/policies/tokenLifetimePolicies

I have test tenant, so no policy exists.
2. Let’s Create a new Lifetime token Policy.
Use Json value as mentioned in table change Display name\Policy hour (8:00:00) eight hours as per your need and post it.
{ “definition”: [ “{\”TokenLifetimePolicy\”:{\”Version\”:1,\”AccessTokenLifetime\”:\”8:00:00\”}}” ], “displayName”: “Eight Hour Token policy”, “isOrganizationDefault”: true } |
Snapshot.
Response

Seems all ok with 201 return code.
Time to validate whether access token is showing 8 hours expire window.
Re-Generate a new token from Part-1.

All good token is showing 8 hours expire window.