If you look for it in the documentation you will find the following topic https://docs.sdl.com/LiveContent/content/en-US/SDL%20Web-v5/GUID-EF85DD70-BC3A-4C54-A01A-AC65AE83EA83
You can install the Publisher on one or more dedicated machines. On a dedicated machine, you can configure the Publisher for a multiprocessor machine, or increase the number of Publisher threads. You can also create Publishers that only accept content from certain Publications or Publication Targets, or with a certain Publish Priority.
Which confirm that it is possible. As to how to set it up, you need to dig a little deeper in the documentation. The above mentioned number of threads can be configured in the SDL Web Content Manager configuration (MMC Snap-in) under Publisher settings, see https://docs.sdl.com/LiveContent/content/en-US/SDL%20Web-v5/GUID-863D3D2F-380D-48B3-A4B5-E195FDE7A6A8
The filtering on Publications as requested by you can be set in the Queuing settings: https://docs.sdl.com/LiveContent/content/en-US/SDL%20Web-v5/GUID-655433CE-6AB3-4A21-AE4C-A263A92C9FF9
Please note that if you set it up exactly as described, once you add a new Publication C, its publish transactions will never be picked up out of the queue, unless you change the configuration of one (or more) of your Publisher boxes. It is therefore advised to always leave at least one Publisher unfiltered.