Tennessee is the largest deep red state in the country. Texas is still pretty Republican, but it's not as red as it once was, Ohio is still trending R, Florida might be getting there we will have to wait and see. But Trump won Tennessee by +23 and it was the state to yield him his largest net win margin of raw votes. Tennessee's size actually pretty underrated, it has a similar population to Arizona, Massachusetts, and Indiana. Regardless, Blackburn is safe and will win by a large margin exceeding her 2018 win.
Tennessee rurals in the eastern part of the state are extremely dense and extremely red. Without the Appalachian part of the state, TN would actually be competitive, but those rurals net the GOP a ton of votes Nasheville and Memphis could never overcome.