Can I put crushed stone on top of sand base for brick patio?
Sand only is acceptable if it’s “contained”.
Sand is an excellent bearing material, but it tends to get washed away by rain.  Sand has small particles that can be washed away allowing the base to settle (often at different amounts).
If the upper part of base is too high and could get washed away, you could put 3/4” minus crushed rock on top, compact it, and then put the bricks on top.
Using a 1” layer of sand on the top allows you to easily install the bricks level. But if you make the crushed rock level and you install directly on top of the sand...and the sand will be contained low enough not to be washed away...the base will remain intact.