Is the typical presidential win much more substantial?
Yes. This is the slimmest margin of victory since at least Lyndon Johnson in 1964.
Do you mean the margin presented in the table here: https://en.wikipedia.org/wiki/List_of_United_States_presiden...
And how does one come up with sufficient margins for the president to do any given thing?
He certainly has no mandate for anything. He only barely won.