wrote :
The reason I ask is rather important. My friend has a heart condition
and needs pressure of 4,000 ft or less.

I would never bet my life on a Southwest customer service rep :-)

I've had an altimeter watch for a around 10 yrs. and always monitor
the cabin altitude on commercial flights. At cruising altitudes above
30K ft. I've always seen a cabin altitude of between 6K ft. (newer
planes) and 8K ft. (older models). I believe the regs call out a
maximum altitude of 8K ft.

John Galban=====N4BQ (PA28-180)