There is no modified BIOS for RX5500 yet. I can get about 28+MH for a stable work. The maximum hash a could get was 29.5MH but there were lots of rejects.
This makes RX5500XT not that good, I believe gtx 1660ti or super are better option over this card unless you get them for dirty cheap price, with 8gb VRAM it should be able to achieve 30mh, such a shame, the only thing the RX5500xt do better is very low power consumption