Migration to a new MAC

The Best Way to Migrate Data from an Old Mac to a New Mac

When you’re ready to setup your new Mac the easiest and most reliable way to migrate your data and files from the old Mac is simply to connect the old Mac's Time Machine external backup drive to the new Mac using a USB cable before you turn on the new Mac for the first time. You may need a USB/USB-C adapter for this; easily found at many resellers for ~$10 or less. 

When you start your new Mac for the first time it will launch Setup Assistant and lead you through the setup process. Eventually Setup Assistant will ask if you are migrating from another computer. You are, so select “Yes” and follow the on-screen prompts to completion!

Never use Wi-Fi for this. It's unreliable and slow.

Ethernet cable connection between the two Macs will also work.

Move your content to a new Mac - Apple Support:

https://support.apple.com/en-us/HT204350

Can you confirm your old Mac's model? The pre-2006 iMacs this forum covered have almot nothing on the drive that is usable on a new Mac. Some of your data files maybe but no apps, utilities, plug-ins, etc.

I have a mid 2014 iMAC 21.5”,

Thank you.I will ask our moderators to move your question the forum section for modern iMacs where it will get many more views and more help.