As I can understand, a refund in freelancing is not mandatory by EU and US laws (correct me if I'm wrong), but still may be a benefit of freelancer's policy for clients.
A quotation from a page about freelancing
Something else you could consider is a refund policy. A written money-back guarantee makes selling new clients on your upfront payment policy easier. It gives them peace of mind knowing they have nothing to lose should you fail to deliver the work.
Think of it as the first few stages of a customer journey map, where you need to build awareness and trust with the company before inking the deal.
Since I'm personally considering to charge clients in arrears after each work milestone, there is no need in a money-back. My client can simply not to pay for the milestone done if he doesn't like it.
The question is, how to properly describe in my policy such a client right without creating a false assumption that I'm just a learner and not a professional expert?
I mean if I would write something like
You can simply not pay for the milestone done if you won't like it
can be implied by clients as
I'm just a learner who fills his portfolio and therefore I anticipate your disliking
P.S. It would be great to hear opinions of the very clients from their standpoint on the subject here