For many years - one receptacle outlet per island, no matter how big the island is.
2020 NEC - changes to require a receptacle based on square footage, less than 9 sq.ft. is one, up to 27 sq.ft. would be two, between 27 and 45 sq.ft. would need three, etc. This was seismic shift to longstanding tradition that caused quite a stir.
2023 NEC - they whipsawed us back the other way, no outlets required as long as there is a means to get power to the island later if someone wants to. If you install an outlet on the island to serve the countertop, it must be above countertop level. Except that some will tell you as written, all you have to do is say that the receptacle in the side of your island is not intended to serve the countertop, and it would then be legal.
Without wading into what language is better and what it should be, I will note that our jurisdiction is amending this section out until the NEC makes their mind up on what they want to do. If we told everyone they did not have to install outlets at islands for three years, and then the next code cycle changes back to 2020 language, the contractors would lose their minds.