Starting with version 9 (Pie), Android includes support for DNS over TLS (encrypted DNS lookups) which can be easily enabled in the Android settings, without requiring a 3rd party app.
To enable it:
Settings > Network & Internet > Advanced > Private DNS
Enter the private DNS service you would like to use. We recommend the following:
Save the settings and check at https://ipx.ac/run if you are using the correct DNS servers.