It is intended to Help by pointing out options to consider as ‘You’ create your Script. In otherwords, you could create GUI with Radio-Buttons and input Fields for Grid Geometry you want, including Line Style.
Yes, I could create a nice script with GUI having input fields for Start/Finish line postions and Styles…etc But, I don’t need the script and doing your work, though could be fun for me, isn’t in my line of thinking how to best Help You Learn. Perhaps others may be willing to do it… It’s pretty simple stuff to do this sort of thing and, if I did do it, there would, no doubt be things you wanted different/added/etc… and would ask for the changes/edits…
For just Line Style change, you create the Script that Edits the PCB-File (using Python’s Search&Replace) or, other Code language…
ADDED: I’ve posted ‘Search and Replace’ code several times on this forum. If you look around you’ll find it and will be able to use it to do as you asked as shown below…
Here is one of my Posts - though it shows editing of Footprint, it will edit any Text file including the PCB-file, so it will be the basis of what you need…