Is there an option for super- and subscript in portable text field? Custom decorators can be added as an alternative.

const sup = props => {
  return (
    <sup>
      {props.children}
    </sup>
  )
}

<BlockContent
  blocks={input}
  serializers={{marks: {sup}}}
/>

{
        name: "richText",
        type: "array",
        of: [
          {
            type: "block",
            marks: {
              decorators: [
                {
                  title: "Sub",
                  value: "sub",
                  blockEditor: {
                    icon: () => <sub>sub</sub>,
                    render: ({ children }) => <sub>{children}</sub>,
                  },
                },
                {
                  title: "Sup",
                  value: "sup",
                  blockEditor: {
                    icon: () => <sup>sup</sup>,
                    render: ({ children }) => <sup>{children}</sup>,
                  },
                },
              ],
            },
          },
        ],
      },