You validate your matching by running monte-carlo simulations and thus you will use the matching provided by you foundry models.
But to get a feel about the parameters, mainly Avt, because it is the dominant one, you can do pretty much what the formula says. Place a pair of devices in schematic with certain W and L. For example you can hook them as a current mirror but make sure the receiving side of the mirror has the same VDS as the diode connected transistor. In simulation look at the difference between the threshold voltages of the two transistors. In normal simulations this difference will be 0 but if you run monte-carlo, it will have some Gaussian statistical distribution. From the standard deviation of this distribution you can find the Avt coefficient. You can also put different amounts of current in the mirror and see if and how much the Avt changes. Place few more pair of transistors like that with 2W, 4W... and extract their Avt too. Ideally they should be the same, but in reality will come somewhat different. You may take the average of them to have just a single number. You will always validate your circuits with running MC which will give you the real mismatch.