When you generate a Solid Layer (one of many kinds of layers you can create) there is a button on the dialog screen that you can click on that says Match Comp Size.
Not quite sure what you are saying. As lasvideo said, the size can easily be set for solids. For everything else you may wanan have a look at the Fayer --> Transform fitting options in teh menu and the associated keys...
The layer is a sequence of stills--jpegs--timelapse.
I want to squeeze the the photos to fit into a 16:9 1080 comp--no black bars--distortion is OK.
I can do this by hand, but its hard to match up exactly--its always slightly over or under the comp size unless I zoom in and drag carefully...
There it is--Layer--->Transform---->Fit to Comp.....Ctrl+Alt+F
Just a note... distortion shoujld never be ok. Croping is better. I'd use Fit Horizontally to eliminate the black bars.
BTW, Black Bars are OK too for most. It's the only way you can watch Cinemascope or Standard movies on a HD TV without distortion. Distortion is bad....
In the context of your vid - not bad at all. Without a point of reference like a human or recognisable sign/logo etc, you get away with it fine here.
And I don't have to make any difficult crop decisions. I get to keep all the sky--where the action is.
To be fair, I already had to crop because of the serious lens correction....
But wait--there was a human in there--ME!! =)
(Too quickly in and out to make the distortion matter...=)
Select File>Scripts>Demo Palette. This will open a palette in AE with a scale comp button. Simply select your comp in the timeline and click. Use should be easy to figure put.
You can also scale/fit layers.