Safari Presentation Mode command line
You could use an AppleScript like that to do it.

tell application "Safari" to activate
delay 3 --adjust to your needs
tell application "System Events"
    tell process "Safari"
        tell menu bar 1
            tell menu bar item "View"
                tell menu "View"
                    click menu item "Hide Toolbar"
                end tell
            end tell
            tell menu bar item "View"
                tell menu "View"
                    click menu item "Hide Status Bar"
                end tell
            end tell
            tell menu bar item "View"
                tell menu "View"
                    click menu item "Enter Full Screen"
                end tell
            end tell
        end tell
    end tell
end tell


Save it with the name you want, and then run with osascript your-script.