That's not really how that works. There's not a section in one's DNA that codes for bones, rather there are sections that code for proteins that get involved in chemical reactions that begin building bones themselves. DNA codes for chemicals that when they come together at the right time produce your fingers for example. It's not that the DNA codes for a 32mm birth canal it just codes for the proper chemicals to come together to begin developing what will eventually become the birth canal.
So editing the DNA to modify a particular physical aspect is not just reprogramming a new number somewhere in the DNA, it's coding for more expression of particular chemicals to come together. But like anything, adding more reactions can have various side effects, having those chemicals linger for too long and the tissue may eventually become too frail to even give birth to begin with.
You know, like utilize our knowledge of DNA to fix known issues as such
And that's easier said than done. Editing DNA isn't something we regularly do and when it is done, it's usually done on something simple because editing usually results in a 99% loss. Long story short, editing haploids (and most likely male sperm) is going to be the primary means for germline genetic editing that "might" be passed on to children because most people are not ethically okay with attempting to edit embryos with a 99% failure rate.
But editing haploids doesn't assure that the trait will be conveyed to the offspring. During combination some of the genetic material is mixed around in a sort random fashion. So that new trail could get mixed around and now you've coded for a pregnancy that might end in miscarriage or even worse, might not.
It's really complicated and incredibly error prone to edit DNA. Which is why it is mostly done with sperm, yeast, bacteria, and what not. Things that if we kill 99% of it, isn't some big ethical concern. Editing an embryo is like rolling ten million dice and every single one of them have to land on six otherwise you've just doomed that person. That's not an impossible thing, just a highly improbable thing and no one is really comfortable with those odds from an ethical standpoint. We're not really good at editing DNA correctly the first time, but given enough of something, we can eventually have success. So if the odds are one in a million and you have 500 million of something, then you've got really good odds at success.
So you should keep that in mind when you think about editing DNA. Even if we got really good at knowing which genes to express and which ones to repress (which we're not even there yet), putting in those changes that would actually make it to the offspring would also be monumental. So yeah, we're not anywhere near where I think you think science is at.
start growing people in a lab
I also commented elsewhere about this notion. But also, even if we did have an artificial womb today, it's likely going to be in the NICU of your local hospital and not some laboratory. Because an artificial womb, as I indicated in my other comment, would only really be for preterm births greater than 22 weeks gestation, which is way better than what we get with incubators that only give moderate success rates at 28 to 32 weeks gestation and are ideally for 32 to 37 weeks gestation.