Found this Reddit Thread where another User is asking the same question. One User gave a good answer but don't know how reliable it is: https://www.reddit.com/r/Amd/comments/pci9lx/amd_5600g_how_many_displays_does_it_support/
Neither CPU World nor WikiChips indicates the maximum displays the 5600G can support.
Found another CPU Spec website and it mentions the 5600G uses Radeon 7 Graphics (Renoir): https://www.cpu-monkey.com/en/cpu-amd_ryzen_5_5600g-1877
At CPU-Monkey for the Ryzen 4600G is also shows a maximum of 3 Displays for the Integrated Graphics: https://www.cpu-monkey.com/en/cpu-amd_ryzen_5_4600g
Yet at WikiChips for the Ryzen 4600G the predecessor of the 5600G it supports 4 displays with Radeon 7 Graphics: https://en.wikichip.org/wiki/amd/ryzen_5/4600g
So one CPU Website says the 4600G support 3 Displays and another CPU Website says it support 4 Displays. So at least you know the 5600G supports at least 3 Displays.