Data storage for iMac 2020

Hello! I am in the process of purchasing a new 24" iMac 2020 (to be delivered next week). I am currrently using an iMac 2011.

I would like to keep all of my data currently on my old iMac. My intention is to use an external ssd for data and keep the internal storage for programs.

I am not sure how to download all of my current data onto the ssd such that it can be read by the new iMac.

In researching on the internet, I have come across partial solutions but have not seen the specific issue of having a permanent ssd based on what is on my current iMac 2011but to be used by the iMac 2020.

Any help would be appreciated.