Can Thunderbolt 5 support two monitors from one Dock?

Yes. But it's not down to the cable, it's down to the dock. The Dock needs to disclose to the Mac that there are 2 displays connected so the display signals can be sent. Only actual Thunderbolt docks will do that.

It's then down to the dock to split the signals to the appropriate ports. The Mac should be able to see 2 displays connected in the Displays section of system settings.

The M4 Pro supports 2 external displays.

The M4 Max supports up to 4 external displays.

for docks that support dual displays from a single thunderbolt connection, good quality ones that actually men ion it.

for example: click here ➜ Cable Matters 40 Gbps 14-in-1 Thunderbolt Dock with Dual 4K 60Hz DisplayPort or HDMI - Amazon.com