Food is the big one that clearly has to change, its not possible to reduce the CO2 impact of meat and that will have to change. Its also going to be required to change the gas boiler for a heat pump or electrical heating, cars replaced by Electrical Vehicles and to stop using airplanes. The electrical side which is making progress is only about a third of the CO2 production and all the other producers also need addressing.

What a lot of personal CO2 calculators currently do is conflate primary CO2 production (your burnt the fuel in your device) and secondary (you bought from a company and they emitted) but things like meat and airplanes we know there isn't a technical solution to reducing CO2 so even though they are sort of secondary uses we still have to count their impact and change out behaviour if we want a habitat humans. The same is not true for transit miles and other goods which often get included but which could largely be made with electricity given the transition that must occur, which is a cost that will fall onto business.