old imac as main monitor or external monitor

The demo uses the imac 2009 model and a cable.
The cable is display port to mini display port.
If you want to connect from macbook pro to old imac,
you can buy a USB type C to mini display port cable.
Where to buy the cable?
Reference link: (for reference only)
1/ DisplayPort to Mini DisplayPort
Mini DisplayPort (Thunderbolt) to DisplayPort (Mini DP to DP) Cable – 3 m – (UHD with 4K / 60 Hz, version 1.2, for PC and Mac, DP male connector with locking function, black) – TOP Series
https://amzn.eu/d/iVYmn4Q
2/ USB Type-C male to Mini DisplayPort
6ft USB Type-C Male to Mini Displayport Cable 4K@60Hz USB C to Mini DP Video Conversion Cable Support Screen Mirroring Mode and Extend Mode
https://amzn.eu/d/4HdvK5a
3/ VGA to Mini DisplayPort
Multibao ThunderBolt Mini Display Port DP to VGA HD Female Adapter Cable for Apple Mac Macbook
https://amzn.eu/d/06aMQhT

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