When I need to run a custom DNS, I often use VPN to get to a router with known settings and this works over Wi-Fi and cellular data since all traffic goes to the VPN where I can control the DNS. This requires time and a server (Amazon web service free tier is ideal for low cost hosting).
Nov 08, 2017 Unlock iPhone/iPad with or without iCloud DNS Bypass Jul 20, 2020 DNS for iPad Free Download | iPad Utilities - Best Free Mar 14, 2018 How to change my IP address on an iPad - Quora
Nov 05, 2019
How to configure the DNS in iOS - gHacks Tech News Jun 28, 2019 How to change DNS on iPad - Tech Khiladi
Comment modifier son DNS sur iPhone et iPad
How to Set up iPad - Unlocator Support Jun 21, 2020