I would opine yes.  I've read neither (I should) but have a general idea of what both are about.  I think reading Confessions would give you a better grasp of City of God plus you would see all of his detractions and corrections he made of himself and go in to CoG with a better overall understanding of where he's coming from.  Just my 2 cents.

Alright looking online to buy Confessions soon enough, however there are so many different variations of the book I am not sure which one is the best and most reliable, and faithful to the original. Any ideas?

I am worried about getting one that is cheaply scanned from a PDF and poorly translated, or even translated by non-Catholics or modern Catholics, destroying the sense of the work.

I remember when I wanted to read St. Augustine's "Confessions" for the very first time and came across the same problem of which version to read. After carefully reading and comparing many English versions, I found that the best English translation by far is the John K. Ryan translation from the 1950s from image classics. It's a Traditional Catholic translation so fear not. I'll post a link to it here for purchase and, yes, I strongly recommend that Confessions be read before City of God. Hope this helps:

https://www.amazon.com/gp/product/0385029551/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=0385029551&linkCode=as2&tag=httpwwwchanco-20 />

Thank you very much, I had seen online that the   translation was good, but I wasn't sure. I will most likely get the one you recommended.

I would recommend Confessions first also, since it gives a lot of background into St. Augustine's thinking that might be helpful in better understanding City of God, which he wrote much latter in life.

There's a decent list of his Work in roughly chronological order here (though there are some uncertainties):
https://en.wikipedia.org/wiki/Augustine_of_Hippo_bibliography

I had the great blessing/pleasure to read nearly all of them in Latin (due to my academic work), and chose Augustine as my (conditional) confirmation name when I was conditionally confirmed by Bishop Williamson.