You can buy 3800 watt elements to replace the 4500 watt units. This is commonly done when the electric is NOT 10 gauge wire with 30 amp breaker. If it is 12 gauge and 20 amp you are limited to 3800 watt elements.
When I worked at Sears during the 1990’s, Sears probably sold more replacement water heaters than anyone. Since they had to cover the entire market, millions of homes were built with 20 amp, 12 gauge wire. For liability protection and not telling customers they needed to upgrade the electric, the 3800 watt unit was almost standard for them. Nowadays with Home Depot and Lowe’s, there is no product training so a lot of 4500 watt units get installed by the DIYer that should not be.
A 4500 watt element uses 18-19 amps. A 20 amp breaker may or may not trip but continuous use the breaker will degrade and the wires may run warm at the connections. The insulation may slowly degrade and get false tripping at the breaker because breakers trip on heat. For a friend who had a problem with the water heater, it turned out the pervious owner rewired the water heater so both elements were on at the same time ( a big no no). Amazing the house didn’t burn down with 12 gauge wire and the breaker internally had fused where it could not trip. It started to trip after a home inspector switched off and on all breakers, then the water heater was tripping all the time. A very short distance from the circuit breaker to the water heater is what might have saved the day.