Plugging in is good.
Block heater will warm the coolant and the natural circulation will assist in warming the entire block, heads, Intake and oil.
It’s also preferable from an emissions point of view (if you care).
/Nerd:
Aluminum has a higher coefficient or expansion than cast iron /w aluminum alloy (typical piston material), therefore if left cold the aluminum would “shrink” around the cast causing less clearance and potentially more resistance. It’s probably negligible, i’m just spitballing. An all forged internal assembly tends to slap and make noises until it’s warmed up because of this too. More clearance cold.
"The most merciful thing in the world, I think, is the inability of the human mind to correlate all its contents... some day the piecing together of dissociated knowledge will open up such terrifying vistas of reality, and of our frightful position therein, that we shall either go mad from the revelation or flee from the light into the peace and safety of a new Dark Age."
-H.P. Lovecraft