how best to add external 4k monitor on iMac if Thunderbolt ports are already used up?

Have the following computer: Retina 5K, 27-inch, 2019 iMac

There's (2) Thunderbolt 3 ports, and currently I am using an audio interface and external SSD drive on them.

If I wanted to add an external monitor running at 4k, what are my options? I really don't want to sacrifice one of the Thunderbolt 3 ports for an external monitor, considering that I also have (4) USB 3 ports.

thoughts?

-ryanguy