None of this is historically true at all. We learn history so we can have informed opinions about trends like this. Nixon was called the "imperial president" because he had more power than any US president since. After that, executive power was reduced significantly until Obama (who expanded it more than any president in US history). Yes, we can talk about why that was and there are reasons Obama did that, but he still did it. Trump just increased at bit over that.

PS They are called "Executive Orders". Decrees are things monarchs give so I expect you aren't an American which explains your lack of understanding of US politics.