In theory, there is no limit to the manufacture of 5g processors, even 28 nanometers can be used to manufacture 5g chips.
The reality is that 5g chip processor 7 nm is a default value. If the value is greater than 7, the score and performance will be lower. A value of 7 or less represents an improvement in performance.
The cheapest 5g processor currently available is the Mediatek 700 processor, which is a typical 7-nanometer process processor.