iCloud phone backup

I lost my iPhone 8 last summer at the beach. I ended up getting a 7 as the replacement but I found out about the iCloud stuff an that I could get all my old pics an contacts an messages back possibly. It still shows both phones on the account but I don’t know how to get it on to the new ironically older phone. Hope this isn’t to dumb of a question but technology is not my strong suit, but if anybody needs a new roof I can get you one for no out of pocket. Hope everyone has a blessed day