Returns/Exchange feature
It would be great if there was a native exchange/returns feature like Zorem Returns for customers to self-manage exchanges without intervention from customer support (https://www.zorem.com/product/zorem-returns/)
This would be very good.
I use a big online shop daily which has a very smooth returns feature built-in to the order overview. You go to an order in your account and there's a button to initiate a return. You can select one or all products from that order to return (if the product is eligible to be returned) and they send you a free returns label via email. Super easy, convenient and effortless because it's all automated and doesn't require you to talk to a support person first.
They also have a customer support contact option right there in the order overview so you can live chat with customer support with all the order data already available in the chat for quicker resolutions. This may also be worth looking into adding to FluentCart.