It's been 4 years since I've been with a "free" 2.5 year old, but this was our experience. The stated policy is that the child can share from your plate at menu locations, can get their own plate at a buffet, or you can order (and pay for) a child's meal, or side item or whatever you'd like at a menu location if you don't want to give up half your meal. However, the menu places we went basically let us order a regular kids meal for the child and didn't charge us. I think one place we didn't like the kids choices and ordered just a side that we did pay for, but they still brought the child a free drink.
I'd say, plan on sharing your plate or paying off a kids meal, but you'll likely be pleasantly surprised by not getting charged.