To change the parameters in a model after x sec we need to pause the model when the Simulation time reaches to x sec
To do this we can use pause simulation using Assertion block Model in the top model
refer to the below documentation for how to create a pause simulation model using assertion block
In the Assertion block dialog box, clear the Stop simulation when assertion fails check box. Enter this command as the value of Simulation callback when assertion fails:
whenever the simulation time reaches to x sec it will pause the model and then user can change the parameters and continue the simulation.