Screen pixels and screen pixel dimensions have nothing to do with print resolution quality.
It's dots per inch or pixels per inch that matter.
As long as you set a drawing resolution, in Procreate, of, at least, 300 dpi ( I recommend 350 dpi ), that is more than sufficient for print quality resolution.
Procreate has an infinite canvas, just like any other sketching/drawing/painting app.
You can set Procreate's canvas for an A3 size drawing canvas, or even larger on the iPad you already own.
The issue with your current iPad will be how much free internal storage amount is left inside, as this determines the amount of drawing layers that can be created as well as the overall data file size of a A3 drawing size at 300/350 DPI/ppi resolution.
Also, your iPad model only has 2 GBs of internal processing RAM.
These are the REAL reasons for purchasing a better iPad for art creation.
Screen viewing pixels do not really matter. Its DPI ( ppi ) processor power, RAM and available internal data storage that matters.
You probably need to look at the recent model iPad Pro models with 6 GBs of internal RAM, advanced CPU/GPU and in as high an internal data storage space model you can budget afford.
IF you are looking for a larger screen iPad to do art on, that is a different story.
A larger screen DOES get you a larger working, viewable canvas.
So, you should look at either the newest iPad Pro models or consider a mid-range, mid priced 256 GBs storage iPad Air 4.
Best of Luck to You!