From Xojo Documentation

Read-Only Property (As Integer )
IntegerValue = aURLConnection.HTTPStatusCode

New in 2019r1

Supported for all project types and targets.

The HTTP status code when using the SendSync methods.

Sample Code

This code reads the HTTP status code after a synchronous request:

Var content As String
content = MyConnection.SendSync("GET", "", 30)
Var status As Integer = MyConnection.HTTPStatusCode