The Heritage Foundation is a think tank, not the RNC. Project 2025 no doubt has plenty of supporters in the RNC thanks to how influential the think tank is, but it's not an official party position. Any left of center think tank could cook up a Project 2028 document and claim it's the DNC's equivalent – it'd have just as much (official) standing as Project 2025.
To be clear, I'm not defending Project 2025, Trump or the RNC. I don't need any convincing that Trump and republicans are following the plan, it's plain to anyway who's passingly familiar with it. What I'm trying to point out is that there's a strange trend for people to place all of the blame for our current state of affairs squarely on democrats and the DNC, ostensibly because of their failure to precisely match the steps of the RNC – steps the RNC didn't even take, in this case.