Not able to highlight the text in bold using Dialogflow messager rich response

Question

I am trying to highlight the text in different colors or bold using the Dialogflow messager rich response and tried below all of this. text text text It won't worked, kindly guide me to implement it.

I have attached the rich response below, here I need to highlight the "OrderNo:" text in bold

{
    "richContent": [
    [
      {
        "type": "chips",
        "options": [
          {
            "text": "OrderNO: CX-00001"
     
          },
          {
            "text": "OrderNO: CX-00002"
          },
          {
            "text": "OrderNO: CX-00003"
          },
          {
            "text": "End chat"
          }
        ]
      }
    ]
  ]
}