Hi Kendal,

It is possible to add custom fields to OutputFormat (so the thing under Settings that tries to obfuscate for users where the downstream is located or which DITA-OT to use, etc).

And it is possible to add custom fields to PublicationOutput (so the language level entry of publications, identified by a languages-outputformat combination).

And that should be possible on your 'Knowledge Center' version as well - if I remember correctly. So I'm a bit puzzled if there was anything specific to your use case criterias...

The flow on Tridion Docs is...

1. Setup the required fields or field (if you want to insert a JSON/XML) using DatabaseUpgradeTool (used to be TriDKXmlSetup on older versions), see in the area of https://docs.sdl.com/806356/393853/sdl-tridion-docs-14-sp3/metadata-setup-structures-reference
2. Depending on your timing, the system recycled the server-side processes... or you can ISHDeploy Restart-IshDeployment or you reboot the server :)  .. in the end as field setup don't change that often, they are read at process startup
3. Setup the new field in the properties in metadataconfig.xml, see https://docs.sdl.com/806356/604608/sdl-tridion-docs-14-sp3/configuring-properties-dialogs 
4. Now you can set them, and save them
5. When publishing
   1. For PublicationOutput fields, the Settings > Publish Xml > parameter PublicationOutputRequestedMetadata (aka Admin.XMLPublishPluginConfiguration.xml) decides which fields need to be exported to the file system for downstream usage
   2. For OutputFormat, then it depends a bit what you want to connect to downstream... as you are an upgrading customer, perhaps https://docs.sdl.com/806356/705940/sdl-tridion-docs-14-sp3/ipublishpostprocessplugin---ishsavefilestorunlegacyscripts 

-Dave

Also the community's related post on the right give pointers... for example community.sdl.com/.../how-do-you-pass-a-parameter-to-the-dita-ot-based-on-the-output-format

Also the community's related post on the right give pointers... for example community.sdl.com/.../how-do-you-pass-a-parameter-to-the-dita-ot-based-on-the-output-format

Or check the following presentation (30 minutes) of the TXS events which outlines the flow and show code samples on how to achieve this in SDL TD 14. Process is similar for earlier versions although some of the used content structures are different.

https://community.sdl.com/product-groups/tridion/tridion-docs/m/videos/4532

The flow explained in the presentation can be used for extending publication output (publication language level fields) as well. Just pointing out this option as you refer to the fact that you can pass on the values from Publication Manager / Web Client.
On the Output Format, you can not dynamically specify a value. It is defined on the output format itself
On the Publication Output level, you can dynamically specifiy a value.

Kind Regards,

Raf