The older 4423 and 4223 automotive Pico scopes had a max input voltage of 100 and utilize a 20:1 attenuator. The newer 4425 and 4225 scopes have a higher input voltage limit, and come with and would use the 10:1 attenuator.
you can use either the 10:1or 20:1 attenuators. Remember to watch out for that when using downloaded reference waveforms or Guided Tests from within the software. If they were saved using a 20:1 and your signal is connected through a 10:1 then remember to adjust scaling, mentally or in PicoScope, if you want both with the same visible amplitude.