How to edit kernel's command line

What do you specifically want to change? There are multiple ways to go about most changes, some easier than others. WiFi tends to have other (non-device-tree) issues, e.g., some WiFi needs an extra firmware package (e.g., see https://www.intel.com/content/www/us/en/support/articles/000005511/network-and-i-o/wireless-networking.html).

I do not personally use the WiFi so there isn’t much I can say about configuring a specific WiFi solution, but unless this is something built in to a custom carrier board, then device tree changes would not be needed. If this is a WiFi question, then probably a new thread on that topic would be the way to start (providing the output of “iwconfig”, “ifconfig”, and “cat /proc/cmdline” in the new thread).