DNS-over-TLS for Android is usable right now.
Android 9 supports "Private DNS" which uses DNS-over-TLS to provide security and privacy for your DNS queries. You can configure it with the following steps.
1) Go to "Settings" → "Network & Internet" → "Advanced" → "Private DNS".
2) Select Private DNS provider hostname.
3) Enter dns.google as the hostname of the DNS provider.
4) Click Save.
@ScottMortimer +1 for encrypting more internet traffic.
All the same, it feels weird to recommend increasing privacy by recommending a google service. I get the trade-offs, but it's funny.
@ansuz
I know what you mean. It is my current default until something better comes along.