Install app to site collection using CSOM C# in SharePoint Online

InstallAppCSOM.cs

string webUrl = "https://tenant-name.sharepoint.com/sites/test/";

string username = "user.name@tenantname.onmicrosoft.com";
string password = "password";
SecureString secureString = new SecureString();
password.ToList().ForEach(secureString.AppendChar);
var credentials = new SharePointOnlineCredentials(username, secureString);

using (ClientContext ctx = new ClientContext(webUrl))
{
	ctx.Credentials = credentials;
	
	var appManager = new AppManager(ctx);

	var apps = appManager.GetAvailable();

	var chartsApp = apps.Where(a => a.Title == "Charts 365").FirstOrDefault();

	var installApp = appManager.Install(chartsApp);
	
	//or Install the app async
	var installAppAsync = await appManager.InstallAsync(chartsApp);	

}

I am not able to get AppManager class - below is the error:
The type or Namespace name "App manager" could not be found.

I was able to get it once I installed SharePointPnPCoreOnline from below link:
https://www.nuget.org/packages/SharePointPnPCoreOnline/

And I need to add below name space in code file
using Microsoft.SharePoint.Client;
using OfficeDevPnP.Core.ALM;
using OfficeDevPnP;