Wilson's Creek National Battlefield Boundary Revision Act of 2021 This bill extends the boundary of the Wilson's Creek National Battlefield in Missouri to include approximately 624 acres of land related to the Newtonia Battlefield identified on the map titled Wilson's Creek National Battlefield Proposed Boundary Modification and dated September 2021. The Department of the Interior may acquire such land by donation, purchase from willing sellers with donated or appropriated funds, or exchange.