Apple discontinued the 27-inch iMac when it launched the Mac Studio and 5K Studio Display, but reports that came out earlier this year suggested that a replacement was in the works. According to 9to5Mac, though, Apple currently has no plans to release an all-in-one iMac bigger than 24 inches in the near future.
If true, that means we won't be seeing a 27-inch model powered by an M1 processor — the recently discontinued iMac still uses Intel chips — anytime soon. Apple reportedly has no plans for a larger iMac equipped with an M1 Pro, Max or Ultra, as well. We also likely won't be seeing one with the M2-powered MacBooks that Apple is expected to launch later this year. 9to5Mac says it got the information from the same source that told the publication about the pro-level Mac Studio and the Studio Display before they were unveiled.
At the moment, the only iMacs you can get straight from the Apple Store website is the 24-inch model with M1 processor released last year. The publication says the tech giant is developing a new 24-inch all-in-one computer slated to be introduced sometime in 2023. However, similar to the MacBook Air and the 13-inch MacBook Pro, it will likely remain one of the company's (relatively) affordable options and won't come with its high-end chips.