How do I get my 2019 MacBook Pro to support higher refresh rates than 60 Hz?
The max refresh rate remains 60Hz.
https://support.apple.com/en-us/HT210742
Available refresh rates
You can switch between these refresh rates on your Retina display:

60 Hertz
59.94 Hertz
50 Hertz
48 Hertz
47.95 Hertz

MEH!