Find, download, install the orbot apk from your favorite source. Maybe the latest version is suggested, but it has new flaws too. Maybe Microsoft github is best Releases · guardianproject/orbot · GitHub , for this (hurts to write it)
Run Orbot app. Read instruction/setup. Choose options carefully. Full VPN or app by app selection.
Android settings, network & internet, advanced (or search VPN), VPN. See or select Orbot. Settings tap Always On, Block connections without VPN if you want it.