Okay, so I got it working. But I believe you do need to use an iframe, or at least that is going to be the easiest way without editing a lot of files. You can't upload the Godot HTML5 export into WordPress, because Javascript (and other files) are not allowed. So you will need to export from Godot, and then copy all those files it gives you to your server somehow. You could use the file manager in cPanel, or sFTP if you prefer. Put them in their own folder. Then in WordPress, click on the block that is called embed, and add this code in there:
<iframe src="https://YourServer.com/YourGame/Game.html" style="width:1024px; height:600px; border:none;" title="Godot Game"></iframe>
That will work.