Hello,
yes, this works with the PDF24 Creator (Windows):
- Open the PDF24 Creator (in the PDF24 Toolbox via the menu "Open PDF24 Creator").
- Open the PDF file with File > Open....
- Click File > Save as... and choose the format PDF.
- Set PDF standard to PDF 1.6 and save the file.
The same option is in the Save as... dialog of the PDF24 Assistant, which opens when you print a document on the PDF24 printer.
Please note that the file is written anew during this conversion, not only its version number is changed. Please check the result, especially for files with forms or other interactive content.
Download of PDF24 Creator: https://tools.pdf24.org/en/creator