If you're on a school Chromebook you're probably out of luck, but if you're bringing your own device it's easy. Also keep in mind that DoH is not primarily a censorship circumvention technology, it's a privacy/confidentiality technology; it won't do anything if your school is blocking websites by IP address. Tor and VPNs are more designed for this stuff.
My Android device has a DoH option in Settings -> Network & Internet, but it's a security-focused image so it might not work for you. In Windows there's an option in WiFi hardware settings, and on Linux you can use DNScrypt.
If you're on a school Chromebook you're probably out of luck, but if you're bringing your own device it's easy. Also keep in mind that DoH is not primarily a censorship circumvention technology, it's a privacy/confidentiality technology; it won't do anything if your school is blocking websites by IP address. Tor and VPNs are more designed for this stuff.
Firefox has DoH (DNS over HTTPS) built in for easy use: https://support.mozilla.org/en-US/kb/firefox-dns-over-https
My Android device has a DoH option in Settings -> Network & Internet, but it's a security-focused image so it might not work for you. In Windows there's an option in WiFi hardware settings, and on Linux you can use DNScrypt.
Some resolvers may be blocked, but there's a good list of them here so you can try several: https://dnsprivacy.org/public_resolvers/#dns-over-https-doh