Prepopulated data/lines of code on new Sketch rules

Is it possible to set rules/template that can prepopulate my sketch book whenever i open it/create new. E.g, include headers , or declare variables etc
If this is not doable from plain double click ,then we use any programs or powershell scripts to do the same.?

The sketch outline that is presented when you do File/New is the BareMinimum sketch. Edit that to change the default.