In my house we have slightly oversized trashbags, have the bag oriented the other way (so when you pull the bag out it does not get stuck*), make sure the drawstring is over the lip, and this depends on the design of your trash-can but just see the picture. Image link for non-Kbin.
*= this is specific to a larger bag in a tapered container. If the orientation matches closely, lifting causes it to expand at the bottom when you lift so you’re only lifting the bag at first (also this allows it to get stuck when it’s overfilled). Rotated the other way it cannot expand fully until it is out of the container.
I just checked, apparently we have a ~16 gallon can (15 7/8ths*) and use 33gal bags. It doesn’t seem that much bigger (bc volume) but an overfilled bag will still have room in it when removed (it’s useful for last-minute additions on garbage day).
I don’t know if you need to go this far, but maybe it is why they still fit the can properly with the not-expected-fit orientation like I described to prevent overfilling. 30gal might work, I guess it seems there isn’t much choice here though (otherwise I’d say try 5-10gal/~20% higher rather than double).
*= Rubbermaid 3541, “Slim Jim” not cheap for plastic but we’ve had it for years so I’m not sure if it was that expensive when it was purchased