Substepping worked in UE4 but it required adding custom physics as described here Physics Sub-Stepping - #14 by toxygen
Unfortunately this doesn’t work in UE5, custom physics only gets called once per frame.
It seems like in UE5 substepping works only internally, with no access for the developer.
The only workaround that I know of is this Async Tick Physics plugin - Exposing UE5 TickPhysicsAsync Event - #3 by Claigo