As far as I understand it ( which probably isn’t very far at all), the licence privileges are essentially to do with hire & reward. As a PPL, essentially you have to pay for your flying. If you can afford to operate a 747 privately, you can fly it, subject to having a suitable rating attached to the licence. In this case, it would be a 747 Type Rating. You would need to have passed ground exams covering the theory of air-conditioning & pressurisation, avionics, meteorology, flight planning, gas turbines etc etc, in addition to to the Type Rating theoretical knowledge exam. As the 747 Type Rating includes a multi engine Instrument rating, you would need to have sufficient hours to qualify for one of those too, and a Multi Crew Cooperation course pass.
I don’t think there’s any reason why those ratings can’t be attached to a PPL, but by the time you have done all the above, you’re probably not far off getting a CPL anyway.
Let us know how you get on won’t you!