Hello @Dileepa Mabulage , Azure AD access token lifetime cannot be extended and usually range from 60 to 90 minutes. An exception to the former are mobile and desktop clients that access SharePoint Online and OneDrive for Business resources where you can extend them using Configurable token lifetimes in the Microsoft identity platform (preview).
For more information take a look to access token lifetime.
You can, however, request refresh tokens which can be used to issue new access tokens. The default lifetime for the refresh tokens is 24 hours for single page apps and 90 days for all other scenarios. Refresh tokens replace themselves with a fresh token upon every use.
For more information take a look to refresh token lifetime.
Let us know if you need additional assistance. If the answer was helpful, please accept it and rate it so that others facing a similar issue can easily find a solution.