If by "meaties" you're asking about Cornish X, no.
Technically, the birds can coexist peacefully together without any issues whatsoever. Logistically however, it's not as easy. Your layers are probably accustomed to (and should have access to) essentially free-choice feed. Cornish X, past the 2nd or 3rd week of life on the other hand, will need their feed rationed to ward off fatal leg and heart complications.
As someone else mentioned however, a dual purpose breed can be kept with your layers full-time, will take a little longer to grow out, but will provide some very tasty meat without the need for additional housing. Buckeyes are one breed, but can be a bit more difficult to come by at this point. Australorps, Brahmas, Dorkings, etc. are also options. Just know that in any batch of dual purpose birds you get from a hatchery you will have some that meet breed standard sizes but plenty of others who do not. That is, while the breeds are good for meat and eggs hatchery stock often grows out to smaller sizes than what actual breed standard dictates so your best bet if you go the hatchery route is to plan to keep the best hens and roo out of your first batch for growing your own decently sized birds in the future.