The most common way to "down-save" a file for compatibility with InDesign is by using the InDesign Markup Language (IDML) .
If you recently upgraded and need to switch back to a previous version, you can do this through the Adobe Creative Cloud Desktop App Open Creative Cloud. Find InDesign, click the three dots (...), and select Other Versions Install the desired previous version. how to convert indesign file to older version
If you need to perform this "magic trick" yourself, here is the standard process: the file in your newer version of InDesign. InDesign Markup (IDML) from the "Save as type" or "Format" menu. the file to your desired location. file using the older version of InDesign. the file immediately as a standard to lock in the format. ⚠️ Important Limitations The most common way to "down-save" a file
Converting an InDesign file to an older version can be challenging, and some limitations apply: If you need to perform this "magic trick"