Hi @Umair Aslam,
Thank you for your posting in this community.
For your questions:
1.By default, all SharePoint cookies are session cookies. Reference:https://learn.microsoft.com/en-us/sharepoint/authentication#sharepoint-authentication
As far as I know, it's not allowed to be customized.
2.Regarding the implementation of a cookie consent banner, SharePoint does not provide a built-in feature for a cookie consent banner.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.