I have a 6s I can confirm the app switcher is working on my phone.
It still works on my iPhone XS as well.3D Touch is still supported for the 6S. I downloaded IOS 13.1.1 yesterday and the 3D is working fine on my phone.
Back up your iPhone then erase it and set it up as a new phone. If it now works properly then something in the software on your phone was causing the problems. If it still has problems it may have a hardware problem.I got a 6 s I have problems with my phone all the time. Need a new one
You‘re welcome.Thanks J.A.
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