iPhone 6 Plus

When you get a new iOS device, the "Quick Start" setup process on iOS 12.4 and later can offer you a shortcut by putting the new device right next to your existing one, and the basic account information and data can wirelessly transfer over. More info:

Use Quick Start to transfer data from your previous iOS device to your new iPhone, iPad, or iPod touch - Apple Support

(see the section "Transfer data directly from one iPhone to another")

The article says that you can do this over a wired device-to-device connection, but I don't know of a Lightning-to-Lightning cable to facilitate this, so this is probably in reference to an iPad Pro setup where one could use a Lightning-to-USB C cable.

There is no data on the SIM card. See here how to transfer to a new phone: https://support.apple.com/en-us/HT201269

The chip or sim card only holds your phone number and carrier settings. If you are getting a new sim, or setting up your phone service directly on the iPhone through settings, then you don't need to transfer the sim card. Otherwise you would need to transfer the sim card to get your cell service on your new iPhone.

To transfer your content you follow the migration steps while setting up the new iPhone. Which might involve placing them side by side yes, depending on the method you choose.