GAS Script to change the layout of existsing slide - google-apps-script

Question

I have a Google Slide where
Slide1 has Layout by name "Layout1"
Slide2 has Layout by name "Layout2"
Slide3 has Layout by name "Layout3"
I want to modify the slide layout of Slide2 from "Layout2" to "Layout1" by specifying the Slidename
Hence my input to function will be SlideIndex AND Layout name
Please note that "Layout1" and "Layout2" and "Layout3" are the names of Layouts they are NOT PREDEFINED LAYOUT NAMES
Sample presentation https://docs.google.com/presentation/d/13D5u4mvYF2sNpCpYtyklqxVmMQ5FPV71UoKsk4Zhf8o/copy here is the sample
function changeSlideLayout() {
var presentation = SlidesApp.getActivePresentation();
var slide = presentation.getSlides()[0];
// Change layout to title slide
slide.setLayout(SlidesApp.Layout.TITLE_SLIDE);
// Change background color to red
slide.setBackgroundColor('#FF0000');
}

Answer 1

After doing some research, it seems that it is not possible to update layouts with the Slides API. You can see here the kind of updates to apply to a presentation.
This is a product limitation for Google Slide API, this request can be promoted for future development through here.
What you can do is insert a new slide and apply a custom layout, here is an example if it helps.
function slideLayout() {
var presentation = SlidesApp.getActivePresentation();
var layouts = presentation.getLayouts();
var layout;
for(var i in layouts)
{
if(layouts[i].getLayoutName() == "2_Blank")
{
layout = layouts[i];
Logger.log(i)
}
}
presentation.appendSlide(layout);
}