how to create simulink in matlab 2019b?

Create simulink file

Answer 1

[stozaki]

In R2016a and later versions, launch the Simulink start page before creating the model file.

Build and Edit a Model Interactively

To start the library browser directly, execute the following command.

slLibraryBrowser;

To create a new model directly, execute the following command.

open_system(new_system());

[Walter Roberson]

And note that Simulink is an additional toolbox that needs to be licensed and installed, not part of MATLAB itself.