Spanx- no
Tights- no
Leggings-yes
I personally can not imagine wearing underwear with Spanx. It seems so uncomfortable and that they would loose the smoothing feature. I grew up going to lots of dance classes and we were told not to wear underwear with our tights so maybe I’m just used to it.
Basically anything that has a cotton crotch area are not meant to have underwear worn with them.