It depends on the frame length, and maybe also on the derailleur. The “add two full links” rule is for sram.
If you know your frame dimensions, you can also calculate the chain length in inches.
Chain = 2 x chainstay + front teeth/4 + rear teeth/4 +1
Front and rear teeth are the amount of teeth on you largest chainring and largest sprocket. Chainstay length is in inches.
There is a good article on the parktool website,