26 U.S.C. 2010 gives every decedent a credit for the estate taxes on the applicable exclusion amount, thereby excluding it.
Currently, the applicable exclusion amount is $10,000,000 plus the cost-of-living adjustment (so $11,400,000 in 2019). 26 U.S.C. § 2010(c)(3)(B)–(C). This allows an exclusion of that amount for everyone. (This exclusion is accomplished through the applicable credit amount.)
The applicable exclusion amount is increased by the deceased spousal unused exclusion amount.