During a power outage, you'd typically want to power only the essentials. Of course, if you have a bigger generator, you can power more. However, the bigger the generator, the higher the TCO. So it's important to strike a good balance... especially for folks like me who don't have a bottom-less pit of money.
My backup generator is only 4.5kW (5kW surge). When it's running the house, I turn off breakers to circuits like shower heaters and the oven so that I don't go over-budget on power. Even then, the generator can run all the lights, my servers, PCs, laptops, and two inverter A/Cs (1.5 and 2.5HP, respectively).
I have a couple of ways to monitor power:
On the generator inlet panel...
https://i.imgur.com/cWWnkB2.png
and through the app.
https://i.imgur.com/0MIOjLV.png