updated-1.x-dev/config/schema/updated.schema.yml

block.settings.updated_date_block:
  type: block_settings
  label: 'Last Updated date block'
  mapping:
    date_prefix:
      type: string
      label: 'Date prefix'
    date_format:
      type: string
      label: 'Date format'
    custom_date_format:
      type: string
      label: 'Custom date format'
    timezone:
      type: string
      label: 'Timezone'