Auto generate phrase or value based on data in another cell

[cheeseontoast101]

Hi

Is there a way I can automatically generate a phrase or a number based on the data entered in another cell?

E.g If I entered Chocolate, Milk automatically appears in the cell next to it.

[#2]

You could have a lookup array with your pairings, so if Chocolate should always have Milk and this is know in advance, than a sheet with these pairings and a simple VLOOKUP() (or XLOOKUP if you're on 365) will return the pairing value.
You could wrap this in a IFNA to make it blank until the cell is populated.