It is though. Add HTTPSEverywhere to the toolbar using customize, and you will get the option to enable "Encrypt All Sites Eligible". Working as of Tor Browser 10.0 (ESR 78.3)
Version: 2020.8.13
Rulesets version for EFF (Full): 2020.9.14
Rulesets version for SecureDropTorOnion: 2020.7.30