Duplicate project and Adjust the comp duration using script

This is very easy to implement with Automation Blocks.

This block script opens the project "test.aep" on your desktop, saves it into the file "test copy.aep" and then changes the duration of the comp "main comp" to 10s:

To tweak more than just the duration of the comp, see this tutorial for inspiration:

https://mamoworld.com/docs/automation-blocks/tutorials-ae/writeCustomTemplateTool

And here is a sample block script that is included in Automation Blocks and which created comp duplicates based on a spreadsheet: https://mamoworld.com/docs/automation-blocks/tools-ae/compDuplicatesFromSpreadsheet

Check AEscripts.com for all manner of utility scripts. Anything more than that will require a better explanation rather than a generic "Can I...?" question.

Mylenium