How to fill angular textbox in a webview2 with C#

I have a webpage wiht a lot of textbox. I can fill textbox with this code:

webView21.ExecuteScriptAsync($"document.getElementById('txtPerson_FirstName').value='John';");

But this code doesnt work on a textbox. This is textbox source code :

<input class="form-control ng-pristine ng-valid ng-not-empty ng-touched" name="Quantity_Amount" ng-model="line.Quantity_Amount" ng-keyup="totalCalculator(line,line.AllowanceCalculatorType)" style="width:100%" type="number">

How can I fill textbox in C# using webView2. Thanks