If you wanted to see what would happen, you could edit the script and add the WhatIf parameter to every changing command but that’s not really a viable solution. What you can do is
this will set all commands that accept WhatIf to use the WhatIf parameter. This means that if you are using functions that you have written internally you must ensure that you write your functions to use the common parameters
Once you have set the default value for WhatIf as above, you can simply call your script and see the WhatIf output
WhatIf is a great parameter and when developing cmdlets, you should add in support.