Hi! Welcome to the forum!
Just to warn you, I have no personal experience with this but know some people who have, and they found that Flemish Giants wreaked havoc on their meat rabbits...they got big but lanky carcasses with lots of bone and only moderate flesh...and they have told me that their Flemish and Flemish crosses consumed a LOT more food than your average commercial-type rabbit.
Someone above suggested a smaller breed...I just got a small starter-herd of some very nice Mini Rex to show, and they are really teeny little goobers (so darn cute) but any that are not show-quality will be used as a meat rabbit. They may be small but they are just as tasty, plus I'll get adorable little plush furs from them.
With a smaller breed you'll have smaller carcasses but they don't consume much feed, and as their litter sizes are usually smaller you won't have an overabundance of rabbits.
Someone else suggested Florida Whites...those too are great little bricks of meat. I was admiring a few this past Sunday at a show, they are SO compact and SOLID. Really nice, and they're a pretty small breed with a high meat yield.
Basically, my point is that overall size isn't as important as meat-to-bone ratios and growout times and feed requirements. Ideally you want quick growth of a rabbit that has a lot of meat compared to bone mass, with minimal/moderate feed consumption. To my understanding, Flemish and Flemish crosses grow slowly, get honkin' big bones, and eat a tonne while not producing a whole lot of actual meat.
But! If you find the perfect crosses, go for it. YMMV.