Hi @Anonymous
I did an example using Encodian hope this helps for you, first thing you should know is that our source PDF must be store somewhere, in this example I use Sharepoint, but there are many connectors that you can use in power automate.
First thing I create my source PDF and upload it to my SharePoint tenant.

Then I access the PDF using the SharePoint connector.

Next, I use Encodian to select the source PDF and divide it into pages. For use Encodian you have to create a Apy Key you can do that here.
In the split setting you select the desired pages, i.e. from page 1 to 3 [1-3]. But you can also select different types of division.

And finally you have to create a new file with the new pdf, in my case I use SharePoint again.

I also create a parallels branch to make all the splits in the same flow, here is a screenshot of the complete flow.

And the final result

Hope this can help you, any questions or comments just let me know.
Cheers.