Split post or page content in two or more columns

If you’re using the Block Editor, use Core’s column blocks.

If you’re using the Classic Editor, make shortcodes for Bootstrap’s rows and columns. When you enter content, you can then just enter

[row]
[column large="6"]First column content[/column]
[column large="6"]Second column content[/column]
[/row]

(You may find prebuilt shortcodes out in the wild since this is a common scenario. Or you may want to create your own as only you know which of the column widths you’re likely to need.)