If you need to open Arc from the command line, maybe this could be useful.
#!/usr/bin/env zsh
string="$1"
start="https://"
url=""
case $string in
("$start"*) url=$1;;
(*) url="https://$1";;
esac
echo $url
osascript -e "tell application \"Arc\"
make new tab with properties {URL:\"${url}\"}
activate
end tell"