您可以使用PnP CSOM核心的 GetAppOnlyAuthenticatedContext 方法.

You can use the GetAppOnlyAuthenticatedContext method of PnP CSOM core.

之后，您可以使用以下代码:

After that you can use the code as below:

string siteUrl = "https://xyz.sharepoint.com/sites/MyList/";
string clientId = "<client-id>";
string clientSecret = "<client-secret>";

using (var clientContext = new AuthenticationManager().GetAppOnlyAuthenticatedContext(siteUrl,clientId,clientSecret))
{       
    Web oWebsite = clientContext.Web;
    ListCollection collList = oWebsite.Lists;
    clientContext.Load(collList);
    clientContext.ExecuteQuery();
}

要添加PnP CSOM核心，请转至项目参考>管理nuget程序包.

To add PnP CSOM core, go to your project references > manage nuget packages.

添加SharePointPnPCoreOnline程序包.

Add the SharePointPnPCoreOnline package.

参考-使用PnP身份验证管理器对SharePoint进行身份验证

公开曝光将您的SharePoint Online信息网络化