If you need to implement your own physical calculations independent of frame rate - you can implement it in C++. To make these calculations independent of the frame rate, they must be performed in a separate thread, which is quite difficult to implement in blueprints due to restrictions on access to data in memory, which are necessary for correct parallel processing in different threads.
For the build in physics calculations you can enable in the project settings asynchronous physics calculation mode, which is independent of the frame rate: