Up to a point, Lord Copper. F1 restrictions as just as strict as anything the UCI has come up with, albeit differently. Teams MUST design and build their own chassis, they MUST use a power unit with a 1.6 litre turbocharged V6 petril engine and cunningly-wrought hybrid-electro-Stuffs, they MUST use the same engine management software co-developed by McLaren and Microsith, they MUST use Pirelli tyres, and so on ad infinitum. In practice the teams all use similar software for designing the things and hence they all look angularly alike under the paint job. Except the 2020 Red Bull, on which it appeared that the tip of the nosecone had fallen off even though it hadn’t.
IndyCars all use the same Dallara chassis and Xtrac gearbox, and can use a Honda or Chevrolet (OK, Ilmor) 2.2 litre turbocharged methanol-fuelled V6. No hybrids until 2023.