Using old imac 27 as second screen to new 24” imac

How do I connect my iMac 27″ 5K macOS 13.6.3 as a second screen to my new iMac M3 8 core cpu 10 core GPUv24” macOS 14.4.1? (The 27” is a working computer but is very slow. )

I get the following error message when I try connecting them: “Carnot use Thunderbolt accessory- connect accessory to a Thunderbolt port on this(24”) Mac,” which is where it is.Moving the cable to any of the remaining ports doesn’t connect either.

Do I need a Luna adapter or something similar?