Transitioning between conduit sizes and types using a threaded bushing
I'd get a weatherproof box with 1&quot; hubs on it
Amazingly enough, weatherproof boxes with 1&quot; hubs are a thing, although you may have to order one in through your nearest supply house (or online) instead of just stopping by the nearest big-box store. I would use one of those instead of trying to field-fabricate a swedged reducer down to 3/4&quot;, since you can use reducer bushings in the larger hubs much more easily than you can expand a smaller hub out to fit a larger conduit.