Create dynamic columns for the gridField based on the data.

The following code might be helpful:

= a!localVariables(
  local!CDTFields: split(
    stripwith(
      tostring(
        'type!{urn:com:appian:types:YD}YD_DEMO123'()
      ),
      "=[] "
    ),
    ","
  ),
  local!cdtData: a!queryEntity(
    entity: cons!YD_DT_DEMO123,
    query: a!query(
      pagingInfo: a!pagingInfo(startIndex: 1, batchSize: - 1)
    ),
    fetchTotalCount: false
  ),
  {
    a!gridField(
      data: local!cdtData.data,
      columns: a!forEach(
        items: local!CDTFields,
        expression: a!gridColumn(
          label: fv!item,
          value: index(fv!row, fv!item),
          align: "END"
        )
      )
    )
  }
)

You have to replace CDT name in the above code.

The following code might be helpful:

= a!localVariables(
  local!CDTFields: split(
    stripwith(
      tostring(
        'type!{urn:com:appian:types:YD}YD_DEMO123'()
      ),
      "=[] "
    ),
    ","
  ),
  local!cdtData: a!queryEntity(
    entity: cons!YD_DT_DEMO123,
    query: a!query(
      pagingInfo: a!pagingInfo(startIndex: 1, batchSize: - 1)
    ),
    fetchTotalCount: false
  ),
  {
    a!gridField(
      data: local!cdtData.data,
      columns: a!forEach(
        items: local!CDTFields,
        expression: a!gridColumn(
          label: fv!item,
          value: index(fv!row, fv!item),
          align: "END"
        )
      )
    )
  }
)

You have to replace CDT name in the above code.