I'm not sure there really is a "standard" grind size for AeroPress. I never paid too much attention to the "official" recipe, in large part because it calls for unusually low water temperatures. It seems to me that AP recipes—even championship recipes—are more varied than any other brewing method. Some people go coarse; some go fine. As long as the barista makes appropriate adjustments (dose, temperature, time, agitation, etc.), it seems like you can get good results in the cup with most any grind size.
What you are describing actually sounds to pretty close to a standard drip grind:https://counterculturecoffee.com/learn/...-over-drip
Grind coarsely to roughly the size of granulated table salt.
It's certainly a reasonable place to start. If the brew is bitter (overextracted), go coarser. If it seems sour (underextracted), go finer.