2019 iMac Memory - does 16gb ship with 2 x 8gb

Likely yes, however you should wait for yours to arrive before upgrading the RAM so you know for sure. Also, when you do, please only purchase RAM from Crucial.com or Macsales.com, why, simple iMacs are very sensitive to using quality RAM, both vendors supply quality products, reasonable prices and have excellent service. In short, there is no reason not to buy from one or the other.

Personally, buy it with only 8GB. Then get RAM from OWC or Crucial

as previously suggested. You can purchase 32GB for them, install

it yourself for the cost of Apple putting in 16GB.

In case you never know, order the highest tier 2019 27" iMac from Apple, guarentee RAM is user upgradable to 128 gb. Not that you really need that much RAM.