René is correct. you will need OrcaScript or an external tool like PowerGen.
However, if you plan to upgrade to PB 2021, there is a new tool PBAutoBuild, which provide more powerful functions and will replace ORCA. For starters, it allows you to download source files, merge to PBLs and build the application all in one place. You can choose to just do the download source files and merge to PBLs parts. I recommend that you try it and see if it works for you. It is in beta test period, so your feedback is very important for us to improve this tool.
You can download and install PowerBuilder 2021 Beta to try this tool. The installer link is available in the download center: https://account.appeon.com/download.
Here is the documentation for how to use it for PowerServer project but PowerBuilder project is basically the same. You just need to export the JSON file from a normal application project rather than a PowerServer project in PB IDE. https://docs.appeon.com/pb2021/whats_new/Building_your_PowerServer_project_with_commands.html
Regards,
Tom Jiang