No.
And all textures should be power of 2, so there would really never be any need. keep the plane a square, the aspect ratio will therefore always be correct.
A texture is not a picture. If you want to handle a picture you need to handle a picture. Completely different thing. You probably shouldnt use a material for it.
try looking into the Media player.
Wow! So much help in these two lines (and the one before it) - you are clearly a very smart and useful individual. How about not posting an answer at all?
Here, an example where your much smart could (would it?) fail:
I want to keep aspect ratio on UI for various icons users upload to a server. They can have any aspect ratios and I want to pack them into a material because I’m also masking and animating the damned stuff. How’s that for “all textures should be powers of two” & “if you want to handle a picture, handle a picture” - wow much help!
So, how do I “handle a picture”?