Hi @nawazme88, I do not think that Brand Portal is providing impersonation functionality. I did not found anything about impersonation under official documentation [1], also I did not found this kind of option on Brand Portal where I have access as Administrator group member.
[1] https://experienceleague.adobe.com/docs/experience-manager-brand-portal/using/introduction/brand-por...
To be 100% sure you can also ask your AMS engineer dedicated to mange your Brand Portal.