The original style bypass filter has the restriction made into the inlet port, remove cover and see, should be no larger than 0.0625” or 1/16”.
Regardless of the line size used for a bypass filter you need to be sure there is the proper restriction either as part of the filter or a separate restricted fitting. The smaller line size alone is not adequate.
If you’ve put on a modern spin on filter head to use as a bypass filter then find a filter intended for use as a bypass (usually filters finer than full flow) they may have a restriction built inside the filter depending on model. Still it’d be safe to add a 1/16” restricted fitting to the inlet.
Outlet of a bypass filter drains right into the sump, usually near the pan rail.
