JSFiddle - React, Tailwind, and code Playground

HTML

<select id="fld_country" name="fld_country" class="form_field">
                              <option value="">Please Choose</option>
                              <option value="233" title="US" selected="selected">united states</option>
                              <option value="1" title="AF">afghanistan</option>
    
</select>

CSS

select  {
    text-transform:uppercase;
    }
    
    select > option  {
    text-transform:lowercase !important;
    }