Wow, thought I’d look at selling my XS before the new iPhone is announced and been spammed for the last 24 hours. I’m banned from eBay (long story) and been using Gumtree as an alternative. Since listing my iPhone I’ve had over 20 spammers trying to get me to send my iPhone and be paid via PayPal. Don’t trust this, use cash only on collection. From what I’ve seen they will say something is wrong with it and push back to get refund or partial refund. PayPal isn’t a guarantee you’ll get your money back.
Please avoid Gumtree for selling.
The best way even though you’ll get less is to go via Apple or a third party purchaser of tech.