Every doubling of the channel width doubles the Shannon limit*

* An a gaussian white noise environment, which WiFi usually isn't in.

*If the bandwidth of the Analog Front End (AFE) and Analog to Digital Converter (ADC) / Digital to Analog Converter (DAC) doubles as well. In the real world the AFE of any wifi radio has a fixed bandwidth, with the ADC sampling rate and accuracy being fixed as well. The end result is that doubling the channel width in a wireless network requires a received signal strength that is roughly 3 dB more in real world devices. This constraint is quite visible in data sheets for most wifi cards like here: https://compex.com.sg/wp-content/uploads/2024/01/wle7002e25-...