Will Apple Intelligence be available on my iMac running macOS Sonoma?

Apple Intelligence will be available in macOS Sequoia. If your iMac is a 2019 or later model year, you will be able to upgrade it to MacOS Sequoia after it is released (scheduled for Monday 9/16)

Also see: Apple Intelligence Preview - Apple

and macOS Sequoia Preview - Apple

Don't forget, a form of Apple intelligence is already available even for Sierra, since 2016. Siri. It may not be as extensive as Sequoia, but it fits the pattern of artifical intelligence programming to answer questions and give you computer researched advice for your help.