Have Cloudfare DNS Android App 188.8.131.52 activated on phone. Use on the phone https://www.dnsleaktest.com/ to see your dns. It says Cloudfare.
Create a hotspot on phone. Access the hotspot from laptop. Check the https://www.dnsleaktest.com/ from the laptop. Now the DNS reported being used is not Cloudfare's anymore. Its the ISP of the phone provider.