That isn’t accurate.
When the phone connects with the BSC it tells the tower of its capabilities and the tower assigns it a frequency/technology and the phone must honor that.
Turning WiFi off or on has no effect, but if you drop in and out of airplane mode, you in effect renegotiate with the tower as if you were a new device and it’s kind of a “hack” that allows you to be assigned a frequency/technology again as if you left the area and returned.
Were phones to renegotiate like you suggest automatically, they would create so much traffic that they would be kicked off the carrier’s network.
Finally, the techs at the tower have to know what they are looking for; if a frequency or a few are not properly peaked due to the antenna or for environmental reasons (tree leaves are a big one in the Spring) the tech will need to check that in particular.
If they just check the BSC self-tests it will report everything is OK because the connection works, it’s just for some reason an awful lot of phones seem to be dropping off that frequency and the BSC takes that as the phones driving away or being shut off, not as an antenna/tower issue.
The techs need to know what to look at, as all the diagnostics will come back “Yep, 5G UW, 5G and LTE are all enabled and operational and the tower reports full functionality.”
The techs have to know to specifically check the noise/error rate for devices connecting on the 3.5 GHz band, for example, and they will only see that by checking the logs which few do as they don’t get paid to dig through a 10 Mb log file for 15 minutes looking for issues the diagnostics don’t report.