apple watch software 2.1 and says software is up to date

Hi

First update your iPhone to the latest compatible software version:

Update the iOS on your iPhone, iPad, or iPod touch - Apple Support

Then follow the remaining steps to update your Apple Watch:

Update your Apple Watch - Apple Support

Apple Watch Series 2 models can be updated to watchOS 4.x if the paired iPhone is an iPhone 5s or newer model that has first been updated to the latest version of iOS 11.x

If you instead have an iPhone 5 or 5c, then your devices cannot be updated beyond iOS 10.x and watchOS 3.x.

If you are unable to install the update, then it may help to follow the steps in the second article under the headings "If you need help updating" and/or "If you installed an iOS or watchOS beta or developer seed" as appropriate.