I found the answer by digging around once again and by combining what I found. Here is the code for fullscreen:
if WINDOWS
builder.ConfigureLifecycleEvents(events =>
{
events.AddWindows(wndLifeCycleBuilder =>
{
wndLifeCycleBuilder.OnWindowCreated(window =>
{
window.ExtendsContentIntoTitleBar = false;
IntPtr hWnd = WinRT.Interop.WindowNative.GetWindowHandle(window);
WindowId myWndId = Win32Interop.GetWindowIdFromWindow(hWnd);
var _appWindow = AppWindow.GetFromWindowId(myWndId);
_appWindow.SetPresenter(AppWindowPresenterKind.FullScreen);
});
});
});