Try enable layout adjustment from layout>margins and columns, then from document setup change the page size.
Have you tried printing the PDF at 8.5x8.5? It's about a121% increase. It might be ok and save you having to resize.
If you are not comfortable doing a layout adjustment for the new page size, then:
The printer paper size you mentioned is a proportionate increment. And the size is not varying too much. In this case, please use the "scale to fit" option:
- When printing from ID, in the Print dialog > click on Setup tab > select the paper size of the printer > select "scale to fit" radio button > Print.
Please note that this type of scaling is not always recommended if your output paper size is varying too large, and you have low resolution contents in your files. Scaling up will affect resolution of raster (placed images) contents.