theres two ways
you can brew it hot to extract all the flavors you would normally get and then ice it
or you can brew it at room temperature to extract the less volatile flavors more
the first way you get more acid and citrusy notes (flavors you'd find in hot coffee) but dulled by the ice. the second way is a bit more sweeter and more emphasis on darker richer fruit notes. they're both tasty
the hot way you need to use more coffee than normal (and steep it longer because of that) so when it hits the ice and dilutes you get the right brew ratio and its not watery
i use an aeropress, add about 40g of coffee and fill with boiling water (about 230g) , agitate 30 seconds, brew for 60 seconds (normally 60 seconds total), and then i push onto ice.
you might want to use a little sugar to balance out the bitterness cuz at colder temperatures sweetness is less noticeable but bitterness remains about the same.
the room temperature way i do 1:1 by weight (coffee to water). leave it at room temperature overnight and dilute to taste cuz a cup of that will give you jitters and diarrhea in the next 30 minutes.
room temperature way is much easier. i wouldn't recommend sticking it in the fridge because that would require a much longer extraction time than 1 day (probably 2 days).
you can buy fancy equipment and stuff but they do about the same thing as the above.