Not exactly. This seems heavy on the processing end. I'm looking for Premiere timeline level.
Create Sequence 1 (Settings 16x9). Do all my edits. Add graphics. Add some motion and transition dissolves, etc.
Then I would have two additional sequences that were auto created (1X1 and 9x16). And graphics and motions would be mirrored from what I created in the Sequence 1 "master" clip. All the graphics would be copied but would be auto centered to fit the new frames. I could go in and do some manual size tweaks as needed.
Now someone from marketing comes and says "hey I'd like this graphic to dissolve in slower and trim off a second on another clip"
I would do those edits on Sequence 1 and then those changes would be automatically mirrored to the 1X1 and 9x16 sequence projects.
Yes, I'm trying to create a workflow for exactly the same thing. My current projects include editing large testimonial clips together and I'd like to have my various aspect ratios individually sequenced from the beginning, but I'd need them to be mirrored so my timecode edits would be applied to the separate aspect ratio sequences, which are identical other than having different ARs. My reasoning is that I'd rather manually position the large clip from the getco before it's all spliced up. I color and sound edit the large clips at the beginning without any issues. Luckily for these types of projects, the auto reframe is 99% effective because they clips are all stills and the subject isn't moving. But this could be helpful for some other projects.
My workflow is I have a previously created and saved Premiere Pro project that has three sequences in it. The main 16x9 sequence is for the edit that gets approved. This is the one I send to our team for review and approval. Once approved, I then do a Command+A and select everything and paste it into a 9x16 vertical sequence, and again paste it into a 4x5 sequence. I do a quick review and adjust any shots and graphics. Then I select all three sequences and do an export through Media Encoder and deliver the exported files to our team.
Once you've locked your 16-by-9 edit, duplicate that Sequence two times and change the Sequence Settings to 1-by-1 for one and 9-by-16 for the other. Nudge video as needed for the best framing (you might find Auto Reframe to be helpful) and update graphics for the two frame aspect ratios as needed.
If you're using Apple ProRes source in Sequences with Video Previews set to the same ProRes settings, you shouldn't see a performace hit.