Hi @CJ_Brunke,
There have been a number of requests of this kind. It is not natively possible to have the ability to add options currently.
The only solution I can offer is using table lookup select list and automation.
The form table contains a lookup list column and an ‘other’ column.
The automation triggers when a new submission comes through. It checks if the lookup table contains that “other” entry and if it doesn’t then it creates it.
Once the form link is used again it will have the new option available to use.
You can find this in the publish doc below.
https://coda.io/@dale-cowling/forms-use-automation-to-add-to-select-list-for-future-entries
I hope this helps as a starting point.
All the best.
Dale