When you are working out a payment structure with clients, especially for the first time it can be hard to determine who is real and who is not. All the more so if the clients are expecting services before payment.
It can be the same on their end too.
It is going to be very difficult for you to set up an escrow service by yourself to use it individually when you are working with a client.
I've never seen anyone who does that. It is only when you are working through a freelance platform that makes use of the services that you can enjoy it.