His planned attack on the judicial branch was a step too far for me. Unelected or not, the Supreme Court is still part of the US system of democratic governance and trying to change the workings of the system for near term partisan gain is undemocratic whatever the motivations.

But you're also absolutely right that FDR wasn't ruling by executive fiat and instead also had major legislative majorities backing and enacting his policies. He really wasn't a king so much as the leader of a political juggernaut able to achieve significant sweeping changes unlikely most other presidents. If anything that makes the cheap imitation American conservatives are pursuing even more notable. FDR was powered by a movement based on overwhelming victory in multiple elections in election cycle after election cycle. Modern American conservatives want to translate one historically unimpressive presidential election victory and a narrow, relatively weak legislative majority, into the same sort of seismic generational change. It's not store brand FDR, it's Temu knockoff FDR.