There are some scene controllers, some battery powered and some means powered, which can handle multiple buttons, but they don’t handle multiple relays. You would have to put a smart bulb or a micro in each of your three outside positions and then have the scene controller button press talk to the hub and the hub then talk to the device at the fixture.
That will work fine as long as the smart things hub is working and the smart things cloud is available, but it means you don’t have a switch for when it isn’t.
What I myself do for this kind of situation is leave the original switch in place, put a box cover over it, and then put one of the battery-operated multibutton devices on the wall next to it. That way the original switch is available if needed, but I can use automations as well.
So that’s an option if you want to consider it.
As Karl said, it’s hard to get three radios into a single gang box. There are some multi endpoint devices ( One radio, multiple relays) which should be able to do it, it’s just that they don’t work great with SmartThings.