Thanks for the info John
and for the video Brad
Watched a couple more videos and decided to give it a try on my laptop. I have an RTX 2070s.
After following instructions I turned all settings to ultra just to see what I could get away with. Visually a noticeable improvement.
Started to get stutters around Sydney Harbour but (I'm on Ultra!) at least the buildings weren't melting and the trees, textures looked great.
I'm sure a bit of tweaking will resolve the stutters but atm very happy with 1st results.
Merry Xmas to all.