Which version(s) of InDesign are supported on MacOS Sierra 10.12.6?

Hi @George25369705djx1,

That would be CC2019, see the details at

https://helpx.adobe.com/indesign/system-requirements/2019.html

However, you must know that Adobe only supports the latest two versions and they would be CC2022 and CC2021. Due to this you won't be able to install C2019 via the Creative Cloud Desktop application. You can try and download the older versions of the Creative Cloud apps from the following website. If the links mentioned on the website don't work, then it means that Adobe has discontinued providing the download and genuine installers are not available anymore. Be circumspect if someone contacts you claiming to provide an installer in such a case.
https://prodesigntools.com
-Manan