Can you increase the number of fields in generating QR Codes in Indesign?

Afterthought (aftercoffee) — you can add almost any number and type of fields to vCard codes, even following the standards and defined field names and formats. However, it's entirely dependent on the end reader as to whether those SM links are correctly passed to, for example, a Contacts record. You can have perfect fields with perfect data and generate a perfect QR code that reads and decodes perfectly... but if the QR applet on a particular device doesn't "recognize" a field, it will ignore it; if the Contacts app doesn't have a standard field for that contact type, it won't show it. This is not, as always first assumed, a fault of the QR code itself.

Er, only true in the narrowest sense that most QR code readers will only properly interpret one URL if that's the first data in the encoded string. You could export your whole bookmarks list to a QR code, but not usefully only because no common app would read it back correctly.

But for all the other data types like vCard/BizCard, you can have many fields, and usually as many duplicates of each field as you like. It's all up to code reader to parse them and pass them to a suitable app (like Contacts, Phone, Map, etc.)

As noted in my other reply, the idea that fields are fixed or limited comes entirely from the convenience entry forms of most generators, including IDs. The form entry mode is not required.