In this article, will share steps to fix issue - Sitecore xConnect throwing 403.16 - forbidden
Below are the steps to resolve:
1. go to IIS and select your instance's xConnect site. (Let's say mylocal.xconnect)
2. double click on SSL Setting
3. update settings as below
4. Now hit your instance, (e.g. https://mylocal.xconnect)
Hope this work. If still issue please comment.