Any old iphone (Renfrew PA4)

I volunteer in my local library helping folk who are having issues with their digital devices. I'm an android user. I'm looking for an old iPhone, preferably, an iPhone 11. This is the oldest iPhone that can be updated to the current version of IoS. Next week I have two ladies with iPhones looking for help and I'm not going to be much use to them, So if anyone has an old one gathering dust in a drawer, please let me know. Many thanks.