How to define options for custom type?

[mikeploythai]

Essentially want to add custom options to a field that uses a custom type as such:

defineField({
  name: "field-name",
  type: "custom-type",
  options: {
    customOption: value,
  },
})

defineType({
  name: "custom-type",
  type: "object",
  fields: [
    ...,
    defineField({
      ...,
      validation: v => v.custom((fieldValue) => {
        if (!fieldValue && !customOption)
          return "Error message";
        return true;
      }),
    })
  ],
})

I know it's possible to define custom options by creating a plugin, but I was wondering if that was the only method?