Sideways flip horizontal toggle switch plates were commonly installed in homes in the 1970's and 1980's. They use a duplex opening, which are also used to cover a duplex outlet. Available in a variety of finishes, all UL listed and made in America.
Sideways toggle switches fit the exact same switch plate as a duplex outlet.
Remove your old switch plate from the wall and look at the base of your horizontal toggle switches. The shape of the base should be identical to a duplex outlet.
If you have Horizontal Toggle Light Switches, you'll see a single screw hole in the center between the top and bottom switches. You will need a duplex outlet cover or combination switch plate with a duplex opening.
If you have Despard Toggle Switches, which are smaller than horizontal toggles, you'll see that they are mounted in a bracket and the screw holes for the switch plate are at the top and bottom of the bracket. You will need a despard wall plate.