Can the end user install more memory to the new iMac?

To follow up on dialabrain's advice, since 2012 iMacs have sealed cases and are very hard to safely open for service or upgrades. Apple will not upgrade RAM after purchase, and it turns out many Apple Authorized Service Providers will not attempt that work either.

Consider the 21.5-inch model "non-user upgradeable." Buy plenty of RAM now, or get s 27-inch model. With the 21-inch models, what you buy today is your "forever RAM."

A 27" iMac Yes, a 21.5" iMac is difficult at best.