Programmatically add field (because UI isn’t working)

Hi there.

I have a pod with 18 fields that refuses to add another one. Other pods with less fields are working. Tried creating a new pod with 19 fields and that one failed to save too. Troubleshooting is more of a headache than getting any positive results so plan B, how can I programmatically add a field in a pod?
I looked through your documentation but there’s several pages missing on the documentation site. I found ways to add items to existing fields but not how to create new fields.
I’d only need to do this once.

Appreciate any help. Thank you.