Is it possible to move 30 seconds before the end of the video?

Hi.

I have two questions.

01-Is it possible to move 30 seconds before the end of the video?(Each File)

02-Can’t I use Main Comp Layer Opacity in the Output Options or Siphon?
https://youtu.be/6er0oyEEjgI

You can add Marks in your videos as jump to cue points, or set the out for the video at 30 seconds prior.