Ovens are generally built as simple devices, and toaster ovens even simpler.
The vast majority of electric ovens out there use a resistive heating element hooked to a thermostat, usually a mechanic one. They cycle on and off during the baking period, with generously chosen set points for turning on or off.
I am quite sure that the ovens don't cycle during the preheating phase, or rather, that for most ovens, "preheating" is just the time until the first time the thermostat turns off. Logically, this also means that the heating element is going full strength during that time - I haven't ever seen ovens which try to regulate temperature by reducing the electricity flow.
Even if there are full ovens which work differently than that, I doubt that there are different toaster ovens. First, both preheating and temperature control are much less important, or physically possible, than with large ovens. Their whole point is that they heat much more through direct radiation than through conduction and convection from a constantly warm environment. Second, they are much cheaper, so the producers stick with the simplest, most well-known, and cheapest mechanisms possible.
This is not to say that you will never ever find a toaster oven that doesn't try to do it in some fancier way, because it is certainly possible to build. But there is no incentive to have it any other way, and I haven't seen it in the wild, so my educated guess is that anything else would be a rare outlier.
The above assumes a classic toaster oven, which is controlled by mechanical knobs. If you have an oven that is controlled by electronics (recognizable by a display and/or touch controls and/or words like "smart", "electronic" etc. in the name) then all bets are off. Any of them can be programmed in a different way from the next, and even in ways which don't make sense for cooking, and you have no way to know what yours does.