Eventually you'll learn how the bots play, and you can fairly easily bait them into doing stupid stuff at early levels. Generally speaking, this is just from getting more experience. You can intuit when they're going to attack you because they normally just walk up to attack the minions. Just get used to backing up when they walk forward, and let them push you under turret and farm there.
While it's certainly possible to do 2v1 against bots at early levels with little effort when you learn what to do, I'd still avoid trying to do that if you're learning. Mindless aggression against bots is a bad habit to develop, since it can translate into mindless aggression against players. Better to play against bots and just farm to develop a solid foundation of play. It's easy to learn how to beat a player in a fight, it's hard to unlearn always trying to do it.