iMac (mid 2017)Is there a USB hub that can be plugged into the thunderbolt outlet?

Yes. The Thunderbolt-3 ports also double as USB-C/USB 3.1 ports. You can use any generic USB-C hub, but I would suggest avoiding hubs that advertise pass-through laptop charging unless they come with their own power cable: the last one I used failed to provide device power when used as a bus-powered device for a desktop Mac.

with my iMac i use a SABRENT Multi-Port iMac Hub. it plugs into the TB3 port, secures to the iMac, and doesn't take up space on my desk.

No but there are Thunderbolt docks that have USB ports and additional Thunderbolt ports and other ports too. I would begin looking at OWC Docks, Hubs, Docking Stations, and More (macsales.com)

You also may find this article valuable Best Thunderbolt 3 Dock & Hubs For MacBook Pro / Air in 2021 (techbrane.com)