Around here, the biggest WH you will find stock for 115 is 20 gallons. Larger versions can be ordered.
Rheem makes a 38 gallon short at 31 inches, and a 47 gallon short at 32 inches. Both are standard 220, so you would have to order it at 115.
At 115, you will have usually 1500 watt elements, and at 220, you will have 4500 watts, so it takes 3 times longer to heat the water at 115, but installing a 220 branch circuit is not a good first-time DIY electrical project.