Not an expert, but I am familiar with the basic concept of capital gains on the sale of real property being subject to tax.
Yes, real property inherited upon the death of the owner generally receives a step-up in basis and the new owner takes the property with a new basis, which is the property value as of the date of death. But your post I quoted is about heirs selling property, with no mention of when that sale might occur or what the value at the time of sale might be. If the property being sold is not a primary residence, any gain in value from the date of the previous owner's death to the date of sale will be taxed as a capital gain, either short term or long term, depending on how much time elapsed. If the property is a primary residence, as defined by the IRS, and certain timing rules are satisfied, up to $250k of capital gain is exempt for a single person, and $500k for married couples. This has nothing to do with the value of an estate.
https://www.investopedia.com/ask/ans...inhomesale.asp