Can I use my old iMac as an external monitor?

Hey everyone! I’ve got an old iMac and I was wondering if it’s possible to use it as an external display for a newer Mac or even a Windows laptop. I’ve heard about “Target Display Mode,” but I’m not sure if my iMac supports it, or what cables/software I’d need. The iMac itself is running really slow, hence the question. The serial number is: DGKMV0E2F8J8

Any advice or confirmation would be greatly appreciated. Thanks in advance!