Most of the time a 1/4" connector on the rear of a keyboard is for headphones.

When you find a keyboard you're interested in, visit the manufacturer's website and download all the manuals for that keyboard. That way you can compare features.
Jim Fogle - 2021 BiaB (842) RB (Build 8) Ultra+ PAK
Cakewalk - Zoom MRS-8 recorder
Desktop: i7 Win 10 build 2004, 12GB ram 256GB SSD, 4 TB HDD
Laptop: i3 64bit Win 10 build 21H1, 8GB ram 500GB HDD
Music at: http://fogle622.wix.com/fogle622-audio-home