3G/4G/5G are generations of protocols for cellular communication, they can run over many different physical frequencies.
Their standards committees agreed on certain bands of frequencies, some with more capacity than others.
I'm not an RF engineer, but given 5G can operate on frequencies higher and lower than 2.4Ghz, then I don't suppose there's any reason you couldn't if you were hacking up your own transmitters/receivers. A regular phone wouldn't, though, as they don't have 5G radios that can talk on those frequencies (or they've got hardware filters of some kind to ensure that they don't).
Their standards committees agreed on certain bands of frequencies, some with more capacity than others.
I'm not an RF engineer, but given 5G can operate on frequencies higher and lower than 2.4Ghz, then I don't suppose there's any reason you couldn't if you were hacking up your own transmitters/receivers. A regular phone wouldn't, though, as they don't have 5G radios that can talk on those frequencies (or they've got hardware filters of some kind to ensure that they don't).