You can utilize AI features within Microsoft Word, without having to add-in any third-party AI tools, by using the Editor feature. This feature will take your current Word content and analyze it and provide improvement suggestions for things like clarity, conciseness, grammar, and other aspects to help you sound more polished in your content.
To use this feature, when in your Word document, click on the Editor button, on the Home tab on the ribbon.
Word will do a quick analysis of your content and open the Editor panel with the results.
If you see a number next to any of the aspects, you can click on it to see the suggestions for that aspect.
This then takes you through each item found in that category where you can ignore or make the suggested changes.