I have the Note 20 (sans the ultra) it doesn't have a 🧭 nor does it have the edge panel option. yet my Note 8 that I traded in did. leads me to download a app for a compass only. I'm not even sure it has a ruler. however I'm sure its AR capable for measurements via a APK.
There must be an issue with your Note 20 if you don't have edge panel available. Try this: