When creating multiple columns, either through page format or inserting sections, is it possible to have them separate? As in I can click in 2nd column and write in it without having to fill up the 1st column?
Usually one will expect text to float over the columns like over pages. So you can not fill the second without manual precautions to leave the first blank.
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Depending on your needs you could use a table or work with frames side-by-side, if you never need the text to spill over to the second column. In traditional setting you would need to work with page/column breaks.
Multi-column pages or sections are only a means of distributing differently the sequential flow of text. Think of it the same as you fold a sheet of paper. The sheet is still a single piece. You can’t use a “pane” as an independent sheet.
Depending on what you write, you can do with table. Contents of each cell is independent from the others and remains confined in the cell. The tallest cell in a table determines the height of the row. If you configure adequately your table, the cell may flow on next page, the table keeping the same geometry.
Another possibility (you didn’t describe your purpose) in the 2-column case of “term and definition” is to use a hanging indent paragraph. Where you have no word to define (the paragraph is continuation of the previous one), you just press Tab to jump to the definition part.