How to create a dropdown button in text field

I'm not entirely clear what you're asking for.  But with respect to Appian components, you're pretty much limited to either a dropdown field or a text field.  For instance if you have a text field it's just that - there isn't exactly the ability to "add" a component of a different type to it, though you could put both next to each other.  I'm also not entirely sure what you mean by "drop down button" - could you expand on that?

Thank you  Mike for your time I will try to enlighten  it ,what’s my scenario is in grids editable grids are there right in that we choose fields like text field or integer field right ,in that text field inside we want to choose drop down ( within the text field we want to choose drop down field) how can we do that Mike. Thanks in advance

Are you looking for something like a picker, so that a few options show up once you start typing? If so, take a look at this recipe.

Since a 'Text' field is open-entry, it sounds like you are looking for a dropdown field to choose field types?

a!localVariables(
  local!fieldTypes: {"Integer","Text","Dropdown"},
  local!selected,
  
  a!dropdownField(
    label: "Field Type:",
    placeholder: "-- choose --",
    choiceLabels: local!fieldTypes,
    choiceValues: local!fieldTypes,
    value: local!selected,
    saveInto: local!selected
  )
)

Since a 'Text' field is open-entry, it sounds like you are looking for a dropdown field to choose field types?

a!localVariables(
  local!fieldTypes: {"Integer","Text","Dropdown"},
  local!selected,
  
  a!dropdownField(
    label: "Field Type:",
    placeholder: "-- choose --",
    choiceLabels: local!fieldTypes,
    choiceValues: local!fieldTypes,
    value: local!selected,
    saveInto: local!selected
  )
)

Thank you for your time chris