Lost phone

I lost my iphone 7 (it fell off my car roof and is along the motorway somewhere) and have bought a new iphone to replace it. Luckily I was able to keep my old phone number and have kept all my information. I now want to erase the data on my old phone but am worried if I do I will lose it on my new phone too. Will this happen or will erasing my data from the 7 do just that?