Hi mbf,
Welcome to the Mattress Forum!
As you pointed out in your follow-up post, a box spring is not the same as a foundation. A box spring would have coils on the inside and generally is not recommended for most modern mattresses. A foundation is rigid, and in effect a glorified riser. As such it imparts no comfort to the mattress but only serves to elevate it.
There is more complete information about foundation that address your question in more detail in the foundation thread post #1 here. Of course, you’ll always want to check with the manufacturer of any mattress you’re considering to make sure that any platform bed or foundation you’re choosing meets with their guidelines for support, and also to maintain your mattress warranty.
Phoenix