The threads have been merged. Let's keep this to one thread only.
To fix your problem, you first need to understand exactly what's going on.
Your room isn't getting hot because of inadequate cooling. Wattage is energy and the heat has to go somewhere. The better the cooler, the more efficiently it removes heat from your PC and transfers it to the environment outside the PC. The same components in an ITX case don't create more heat, it's just harder to move the heat from the PC components to the environment.
If you need to cool down the environment, then the only solutions will involve moving out the heat in the room and bringing in cooler air into the environment. One way to do that is to have a fan blowing out the window, but there still has to be cooler air from somewhere else, such as a cooler area in the house, to bring in (which should naturally happen as you're blowing air out the window). If the rest of the house is hot, then it won't cool down your PC room.
If not from a cooler area of the house, you'll either need an air conditioner or wait until the temperature outside is lower than the temperature inside and bring air from outside into the room.
And failing that, your only solution to lower the temperature will be to generate less heat. Which means less wattage. A 3060 will use less power than a 2080 Ti, though with significant sacrifices in performance as well.