Can I still order a 27inch iMac?

You may be able to find Certified Refurbished 27" iMacs in the online Apple Store.

Other World Computing sells used 27" iMacs. I think you only get a 90-day OWC warranty on those iMacs – as opposed to the 1-year warranty on the Apple Certified Refurbished ones.

While Apple doesn’t sell the 27” iMac anymore, you may be able to find a suitable unit at the Apple refurbished store.

https://www.apple.com/shop/refurbished/mac/27-inch-imac

be mindful that the 27" only comes with intel cpus

the next macOS version will only support 2019 and newer

macOS Sonoma Preview - Apple

they don't sell intel cpu macs anymore so the next version after Sonoma may have phased intel cpu support out altogther

When I purchased my 2020 27-in Core i7 iMac from the Apple refurb store in 2022, it landed on my doorstep two-days after I ordered it (in the U.S.). I purposely chose an iMac with only 8GB RAM and then purchased 2x16 GB memory cards from OWC. I also placed AppleCare+ on it so it is covered through Spring 2025.

Don't let "refurbish" throw you. Mine arrived in new packaging and appeared as though new. It has been flawless.

That OWC memory order also (at that time) threw in a free one-year of Parallels Desktop Pro subscription.

Not knowing what Apple plans to announce, I would still wait to order until after the Apple event next week.

Support for Intel is dropping off too, with iMac 2019 and later required for the macOS 14 Sonoma preview.

Unless you need an Intel iMac yesterday, that is.

There's also the 27" 5K Apple Studio Display. Though by the time you purchase that display, an Apple keyboard, and an Apple mouse, you've spent as much as some 27" 5K iMacs cost.

But you haven't gotten the computer …