I’ve got a Bose A20 Aviation Headset that I’ve been using with the Flight Sound X FSX SOLO-GA (GENERAL AVIATION) USB adapter for PC for months now and it works great. It looks like this:
^ I highly recommend using Bostik Blu Tack to hold the Flight Sound X adapter in place.
With my Bose A20 Aviation Headset plugged in it looks like this:
Then all I need to do is make sure I have it selected by clicking on the speaker icon on the taskbar and clicking on Headphones (7- Flight Sound X):

They also have a USB adapter for Helicopter headsets the FSX SOLO-H (HELICOPTER).
In addition they also have a USB adapter for Military headsets the FSX SOLO-M (MILITARY).
When you have your headset up and running I highly recommend setting up Dolby Atmos as Microsoft Flight Simulator supports it, I’ve posted a guide on how to set it Dolby Atmos here: Dolby Access app - Dolby Atmos for (Headphones | home theater) - Active Spatial Sound = On