I have a late 2013 27" iMac, will the Magic Trackpad 2 work with my iMac?

Check "Compatibility"

https://www.apple.com/shop/product/MJ2R2LL/A/magic-trackpad-2-silver

Yes...

System Requirements

Bluetooth 4.0-enabled Mac computer with OS X v10.11 or later.

Connectivity includes four USB 3.0 ports, dual Thunderbolt ports, Gigabit Ethernet, 802.11ac Wi-Fi (802.11a/b/g/n compatible), and Bluetooth 4.0.

https://everymac.com/systems/apple/imac/specs/imac-core-i5-3.4-27-inch-aluminum-late-2013-specs.html#macspecs1

According to Apple's website it requires a Late 2014 or newer iMac.

Yes. I too am on a late 2013 iMac, and I have the magic trackpad 2 and it works just fine.