Sure, on the Schwab PRAP website and app there is a contribution section. The options are for both pre-tax (to $23.5k in 2025) and post-tax ($23.5-70k in 2025), and a dollar amount or percentage of pay for each. Setting them both to 100% makes as much of your paycheck as possible go to the 401k. The pre-tax bucket is filled first, then the post-tax bucket is started and is filled until the total reaches $70k (more if over 50).