Up to now, it was only possible to use columns in Writer’s page styles, sections and frames. One could not make text boxes, including those used in Impress, with text distributed to several columns. Well, there are workarounds like using tables, but indeed that was not the same, and was breaking the text flow.
Introduced simple columns in text boxes (you just set up number of columns and spacing between them, no per-column width or spacing) are supported in Open Document format files (ODT/ODS/ODP/ODG). At the same time we also introduce support for the related feature in PPTX (tdf#118458) and XLSX files. That improves interoperability. However mind that multiple columns in text boxes are not supported in Word and its file formats, thus columns that you set up with this new feature in text boxes in Writer, can not be exported to DOCX.
The new setting is available in the “Text Attributes” dialog:
This is how it looks in current master:
This feature will be available in the future LibreOffice 7.2, and the next Collabora Office update. If you want to try it, you may take latest Collabora Office snapshots on this page.