Hi Eric, choosing a Dutch oven that is an appropriate size for the amount and type of dough you're baking can certainly be helpful. Using a Dutch oven that is much larger than the amount of dough you're baking is more likely to result in the dough spreading out, particularly if you're working with a high-hydration recipe. While I wouldn't recommend "stuffing" your dough into a smaller Dutch oven (which might result in dough that hits the lid), using one where the sides can successfully support the rise upward is a good strategy. Of course, correct proofing and good shaping also play into how much spread you see during baking. 

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