What's your reasoning? Longer OAL? If so get a Valkyrie.
A large frame 223 would mean proprietary parts that wouldn't make sense to produce. At minimum you'd need magazines and a bolt, and then hope it's going to feed. Functioning that large of a BCG may also be an issues unless you mount a CO2 tank on it to run the action. At that point you have a bigger heavier rifle shooting the same weak sauce round.
It would be as disproportionate as A cups on a fat chick.
It would be like a male pornstar with a micro penis.
It would be like using a honda civic to build a drag car.
It would be like getting a 22LR conversion kit for you Barrett M107.
It would be like putting a counter sniper scope on said Barrett M107.
For some ideas, it's best to lay down quietly until they go away.
Yes Walsh, 2.45" oal or so would be of interest.
Smarter guy than some here put the 223 in the Desert Tech. Many want it in an AI if it were done.
New cartridges , not a case made for some of those quite yet.