Can my 1 year warranty be renewed?

I believe you have 60 days from date of purchase (at least in the US) to add an eligible AppleCare+ plan to a device. True, you have 90 days of support post purchase, but the plan needs to be purchased within 60 days.

From the link you provided:

• In most countries and regions, you can buy AppleCare+ within 60 days of your device purchase. In Japan, you can buy AppleCare+ within 30 days of your device purchase. In China mainland, you can buy AppleCare+ on your device within 7 days of your device purchase or in an Apple Store within 60 days of your device purchase. (At the Apple Store, you'll need to bring your proof of purchase, and we'll inspect the device.)

Only within a 90days window after purchase

Buy an AppleCare plan - Apple Support

for what reason?

because it was repaired or replaced with another model under warranty?

or are you talking about apple care+ subscription?

I am not the original poster, but I would like to know if it is possible to switch my AW7 to subscription Apple Care +?