My iPhone 8plus broke randomly and won't turn on so I brought a replacement, but I don't know weather my photos are still somehow on the phone?

I have erased the iCloud data of the phone and removed it from findmy iPhone, which I realise now could mean that I have missed an opportunity to factory reset the phone remotely. However, I want to sell the phone but I don't want my data (photos, messages, emails, bank details etc) to be floating around randomly, is there any way I can erase the phone without having to pay to have it turn on again. Is it a lost cause trying to flog the phone? Thanks