[Inquiry about sweep of threshold voltage for MOSFET during simulation]

How easy this is to do probably depends on the PDK you're using and the models for the transistor. For example, bsim4 has an instance parameter called delvto which allows you to shift the zero-bias threshold voltage. It's probably fairly unlikely that your PDK exposes this parameter on the device instance though - if it did, you could use parameterisation in ADE to sweep this.

Failing that, you might need to add a variable sweep to vary a parameter in the models for the device (e.g. vtho or vth0 in bsim4). Again, your models many not have a parameter assigned for this which can be swept - so you might need to edit the models to change this.

Of course, it's a slightly questionable activity if you don't have control over the threshold voltage in the process...

Andrew