Arxan in autumn is absolutely gorgeous! A word of warning: if you're short on time, definitely avoid the Heavenly Lake and Earthly Lake route. Heavenly Lake has many stairs, which can be tiring, and the viewing platform isn't very high, so you can't see the beautiful colors from above; it just looks like an ordinary pond. Plus, it's incredibly crowded. The same goes for Earthly Lake. I highly recommend visiting Camel Ridge Heavenly Lake and Rhododendron Lake instead. They're truly stunning, spacious, and not crowded at all. Skipping them would be a waste of your ticket price. You can choose to visit other places depending on your time. I'll save the photos of Earthly Lake and Heavenly Lake for last!
My autumn trip lasted a month, experiencing Xinjiang, the Greater Khingan Mountains, and Western Sichuan. It's clear that the best autumn scenery is found in Xinjiang and Northeast China. The golden leaves are shimmering and sparkling. The colorful leaves in Western Sichuan are filtered and appear duller in reality. For autumn scenery, Xinjiang and Northeast China are the top choices!