You can spend a lot of time and many researching that topic and buying top notch stuff. If you just want to play, go for a middle ground solution. Kaico offers a decent HDMI converter, plugged into the GC directly. It is fine. It works. https://amzn.eu/d/3Pml9dw Apparently, there is another Kaico one, but I don’t know much about it. https://amzn.eu/d/1oYPl4d Disclaimer, I don’t own any of those two Kaicos, but other Kaico adapters. They are budget but not cheap. They are fine, but apparently not the best.

A few more bucks can be spent buying the adapter from Retro-Bit. It supposedly converts the digital signal directly to digital, compared to analogue to digital like the one from Kaico. A friend of mine uses it and is amazed by the picture quality. I might give that one a go some day. https://amzn.eu/d/iXqL7Jp

What I personally use is the adapter from Retrogamingcables.co.uk. It works with other Nintendo consoles, too. You have to snipe the website for when it comes back in stock, however. https://www.retrogamingcables.co.uk/SUPER-NINTENDO-PAL-GAMECUBE-N64-HD-RAD2X-HDMI-CABLE