Lost passcode iphone 8

Hi,

My son has given me his old iphone 8. Unfortunately I cannot contact him at the moment so I can't get him to contact his old carrier and get them to get Apple to unlock it so I can use my carrier. To complicate matters when I got it I went through the initial process of setting it up and created a passcode - I have now forgotten the passcode! On the internet it said that if this happened I could restore the iphone to factory settings and simply start from scratch creating a new passcode etc. When I try this the download keeps failing and I keep getting the same request to put in my passcode! What can I do? I can't go into the Apple store because I'm over 70 and shielding. Also I don't want to spend money fixing this problem because I can't afford it which is why my son gave me the Iphone in the first place.

Any help gratefully received!