FDR was faced with two of the greatest challenges to face the US, the great depression and WWII, and he had overwhelming support from the voters in how he was addressing those challenges as reaffirmed in 4 elections in a row. In my opinion that still doesn't justify FDR's extraordinary take on presidential power, and the passage of the 22nd amendment among other things seems to suggest mine was not an isolated view, but it's hard to argue FDR didn't have a unique set of circumstances and a rare mandate.
Some conservatives seem to want to emulate FDR's approach of having the President act like a King, but skip over the circumstances and mandate unique to FDR that "justified" that approach. It might be different if they were trying to build such a massive, enduring electoral mandate by identify some generational problem to solve with real solutions and a man or woman of destiny to embrace their historical moment. But they don't have any of that and are nevertheless jumping to the President=King step anyways, like a store brand FDR knockoff.
In addition to winning his own elections he also maintained large Democratic majorities in both houses of congress. The only branch that opposed him was the unelected one, because every opportunity the people had to consent to what FDR was doing, they gave him not just a victory but an overwhelming one.
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.
