I have updated from 1.8 to 1.16 on my Xiaomi Mi5 (gemini) 2016 mobile phone with success. I only had to flash new recovery image. Then from recovery installed /e/ OS 1.16.
One good suggestion for new people is always check the mobile device support list on e.foundation before buying a new phone. That way you can always get /e/ OS on your phone.
If anyone is interested check this page to find out if your phone has support for /e/ OS
https://doc.e.foundation/devices
p.s. with /e/ OS on my mobile phone I get security updates for my 7 year old phone and it is still functional, also not making new trash and polluting nature with constantly buying new mobile phones just because the old phone loses official support and security updates or is discontinued. This is really important to me.