How do I achieve a resolution of 8K@60Hz, or a higher refresh rate?

The supported resolutions for various interfaces of the computer are

Maximum resolution (HDMI): 4096 x 2304 @ 60Hz

Maximum resolution (DP): 7680 x 4320 @ 60Hz

Maximum resolution (Thunderbolt 4): 7680 x 4320 @ 60Hz

So if you need a higher resolution or refresh rate, you can connect via DP or Thunderbolt 4 interface.

If your monitor only supports HDMI, you can opt for a DP to HDMI adapter, but make sure it also supports 8K @ 60Hz.