To model a constant impedance load you can use the active power (P), reactive power (Q) and the rated voltage (V) information. From these values, you can calculate the impedance magnitude (|Z|) and angle (θ) using the following formulas:
Once you have the impedance magnitude and angle, you can set them in the "Impedance" block to model the constant impedance load.
To model a constant current load, you need to know the consumed current (I) and the nominal voltage (V). You can directly use the formula I = P / V, where P is the active power, to calculate the consumed current. Then, you can set this current value in the "Current Source" block to model the constant current load.
You can also input these formulas in the respective blocks given you have defined the known powers and voltage information in the base MATLAB workspace and use those variables.
Hope this helps!