Lina Y wrote:
I would like to know if I should take the offer of a client if their payment methods are not through Upwork.
No. Not only would you almost certainly get scammed big time, you'd also lose your Upwork account because getting paid outside the platform is (obviously) strictly forbidden.
Let me guess: The client is currently communicating with you outside the platform too? That would be another serious violation of Upwork's terms of service...
You are not allowed to communicate with prospective clients outside of Upwork until you are properly hired ON Upwork.