Eh how to set it? Lol I am always at 4G+
Go to SIM Card info and setting
Enable 5G button is there
Also you need to ensure your plan comes with 5G. Some telcos support 5G but not all their plans comes with it. I'm using SIMBA so all plans come with 5G regardless.
2nd thing is coverage. Maybe that area don't have 5G so you only see 4G+. Same example, SIMBA - my office area, non-town, don't have 5G.
Lastly, check with telco if you need to change SIM card to have it support 5G. Older SIM cards usually may have this issue.