Samsung galaxy s10 plus

[BazilBrush]

How to find what 4g or 5g network I am using I am on 02 pay as you go 

[-Robot-]

Not sure what your try to ask? If you on O2 pay as your go and have 5G on your plan (some plans don't always include 5G) then your on O2 5G or O2 4G, it should say 4/5G on your phone usually top right hand corner

[AlexLdn]

Anyway s10 + is not 5g compatible. So you won't see 5g.