What do you mean by find KVL or KCL
I guess you are reffering to KVL as Kirchoff's Voltage Law and KCL as Kirchoff's current law
These are the laws use to solve the circuit or in other words find the unknown/desired variable/parameter in the circuit.
If you have a node in the circuit (where many branches meet) apply KCL and when you have loop in the circuit apply KVL