A single serving method (from James Hoffman YT channel) I use is:
16g coffee
150g water
100g ice
I make the hot coffee using the above 16g coffee and 150g water. My brew time is four minutes. Then, I pour that hot coffee over the ice and stir until the ice cubes are melted.
This is the way. JH recommends go grind a bit finer than normal v60 and to use a slightly larger amount of grounds (16.25g). Personally I brew directly over the ice cubes but I don't think it makes a difference.
You might try the Toddy cold brew method. You take like a pound of beans, grind them up and soak in like a gallon of water that slow filters through a special filter they sell (reusable for 10 uses). Then you keep it in the fridge until you use it. It’s a more mellow, less acidic brew in general.
Some People may consider this sacrilege, but I keep a small jug in my fridge that I pour any extra coffee in. In brewing this would be the solvers method :). 1/4 cup left? It goes in the jug.
Then I use this to make iced coffee.
If I’m completely empty, I’ll brew a pot of French press, and then pour it in the jug to restock.
Cold brew shaken with lots of ice (and if you are me, some simple syrup). Cold brew is strong and smooth, and using more ice in shaker lowers the temp fast so less dilution. Strain over more ice in insulated cup.