Publishers usually announce the release date well in advance. So it might be a good idea to follow book - related news sources or sign up for newsletters from bookstores. They might be the first to know when the new Jonathan Franzen novel is coming out. It could be months or even a year or more away, depending on how far along in the publishing process it is.
Well, it depends. Sometimes authors take a while to publish a new novel. Jonathan Kellerman might be in the process of writing, editing, or getting ready for the release. I would suggest following his social media accounts or subscribing to book news platforms to stay informed.
I'm not aware of any news regarding Jonathan Franzen's new novel at the moment. You could try searching on major book - related websites or following literary journalists on social media to stay updated.
You can try your local independent bookstores. They often have a good selection of new releases. Also, major chain bookstores are likely to carry Jonathan Coe's new novel.