This is my 3rd pair of Wellrox. First pair (Different style)  I ordered up to a size 9 they are quite lose, second pair (link below) I ordered the 8 like I did in these, they fit well.
https://www.amazon.com/dp/B00CX9VXYI/ref=twister_B07CP1J82P?_encoding=UTF8&psc=1

These are very snug on my feet but I like that and the base is different than my other two styles.  Arch support is much more in these.  They make a great addition to my collection. They are a bit short but again I still like them, I would be afraid if I sent back and got the 9 they would be lose and that's not something I wanted in this sandal.