When you start a new Magic: The Gathering Arena account, you can skip the tutorial at any point. You'll still get the rewards associated with the tutorial without having to play through all the games, too!
To do so:
1. Click on the Adjust Options (gear) icon in the upper right-hand side of the screen, then select View Account.
2. On the Account Screen, select Skip Tutorial and confirm your choice.
3. After selecting your avatar, click the gear icon and select Skip Tour to unlock all play modes.