Use ODF

[Dr Paul Leyland]

MS Office has had the ability to save and load Open Document Format files for many years now, as does free software such as Libre Office …

https://support.office.com/en-us/article/Differences-between-the-OpenDocument-Text-odt-format-and-the-Word-docx-format-d9d51a92-56d1-4794-8b68-5efb57aebfdc