The vast majority of women did not wear their corsets/stays "tight laced" as Hollywood depicts.

Foundational garments like corsets and stays are meant to give a certain silhouette, and provide support to the bust like a modern bra, but they accomplish this by spreading the load across a wider area. My wife is well endowed, and is generally more comfortable at the end of a day of wearing stays than a modern bra.

Hollywood and the occasional period joke/cartoon have lead to this idea that women were deforming their rib cages on the reg with corsetry, which is just a load of bull.

For more information I recommend looking up Valerie Steele. Her book "The Corset, A Cultural History" breaks down a lot of the myths associated with these garments. She's also done other quick and dirty interviews you can Google if you'd rather not read an entire book.

TLDR: everything you think you know about corsets is probably a myth.