26" fork on 24" bike: reduce travel on suspension fork
The fork's travel is often regulated by adding/removing or repositioning plastic bottom out and/or top out tokens of fixed height inside the fork. For such a system, one can reasonably assume that two following possibilities are most common.

A decrease of, say, 10 mm of travel is accompanied by exactly 10 mm decrease of axle to crown height. All moving parts of the fork are just getting shifted up by the same distance.

A decrease of 10 mm of travel results in 0 mm of AC length change. This may be the case when the fork's construction decouples travel adjustment from AC adjustment.


It would be less reasonable to expect a 10 mm of travel change to cause an unproportional decrease to AC — where would additional millimeters go to? Again, it should be possible to imagine/make such a fork, but it would not be a feature used/requested by many customers.
In your case, it may be more realistic to try simultaneously reducing both the travel and the AC distance by 50 mm (2&quot;), from 100 mm to 50 mm, thus achieving the desired AC distance and still keeping some of the travel. However, other aspects of the fork's construction may interfere with your plans. It is impossible to say for certain without looking at how it is made inside.