To run the generate function you should use CTRL + SHIFT + P for Windows and Command + Shift + P for Mac OS and then select the "Generate Clamp" option.
In total you have four inputs:
Minimum value (for example: 16px) - the value, the final value won't be less than this.
Maximum value (for example: 24px) - the value, the starting value won't be greater than this.
Minimum viewport (for example: 375px) - the size of the viewport to which the total value will not be reduced.
Maximum viewport (for example: 1920px) - the viewport size from which the value will start decreasing.