If I understand you correctly, you need such “Full Bar Beaming”, only where the rhythm is four 8ths - right?

So that all other rhythms are beamed “beat by beat” - right?

Example: one beam group of {8th - 16th - 16th} + one beam group of {8th - 8th}.

Unfortunately Finale does not have a one-click “automatic” solution that finds and changes the beaming layout, only where there are four 8ths.

A such solution exists for Common Time (= 4/4), but not for 2/4.

If you have a contiguous region with four 8ths everywhere (no smaller rhythmical values), then you can use the Rebeam utility, and Rebeam to a time signature of 1/2.

If there are only very few instances with smaller values than 8ths, consider doing the layout “the other way around”:

Give the region a “real” time signature of 1/2, with a “display” time signature of 2/4.

Then you will instead have to, manually fix the few instances with smaller values so that these few instances are beamed “beat by beat”.