Rooting android device without internet connection
You don't need an internet access to root a devices as far as i know... This might help.. https://www.thecustomdroid.com/samsung-galaxy-s10-twrp-magisk-root-guide/
Don't modify any commands or steps given here.. if things aren't going as described DON'T PROCEED I myself have bricked 2 smartphone so i'd suggest you not to root it if you don't have enough knowledge about rooting!