As @mocelet mentioned, matter won’t fix any local network strength issues. That has to be handled within the specific protocol, in this case Zigbee.
Also, at the time of this posting, Zigbee devices don’t use matter themselves anyway. Some manufacturers of Zigbee devices, like Aqara and Philips Hue, offer a “matter bridge,” which then uses Wi-Fi to connect to the matter controller and bring in some of its connected Zigbee devices. But it’s up to each manufacturer, whether they offer a matter bridge or not.
See the following community FAQ for details on different kinds of matter integrations:
FAQ: What do I need to add a Matter device to the SmartThings app? Do I need a bridge router device?
But again, even if the manufacturer of your Zigbee devices does offer a matter bridge and you choose to use it, that won’t fix your Zigbee networking issues. You have to fix those first, and then you can layer matter on top of it.
Have you had a chance to look at the wireless range and repeater FAQ? It’s old, but still valid, and explains how to set up a strong mesh network. (It has been updated to include references to matter and thread.)
Start with post 11 in that topic (I will link directly to that post). Read it, then go up to the top of the thread and read the whole thing. That should answer most of your questions about how to improve network quality.