It'll depend on the details of the system and also how they choose to calculate it. The first will vary a lot, and I dunno if the second is standardised.

But for example, ICE engine power is worked out at optimum conditions and measured at the crank, typically, so if they chose to quote usable combined power at the wheels the ICE engines contribution would be a lot less.

Presumably it is limited by a control system. In petrol only mode you can get 98 PS and in electric only mode 197 PS but the system doesn't allow you to use full power in combined mode.