Columns in a single Document

I’ve been struggling with this for years. I want the first page of a document to be one column, the next few pages 2 columns,and the last few pages 1 column.There seems no easy way to do this. I tried columns but that changes the whole document. I tried a custom style for two columns and that did not work. So how is it done?
A step by step instruction would be appreciated.

Writer from day 1 to on a Mac running El Captan

See Writer: how 2 columns on only one page? for a discussion of columns.