Is your feature request related to a problem?
Support push down sort on a non-reference expression, for example:

...| sort (a + 1)

...| sort length(a)

What solution would you like?
A clear and concise description of what you want to happen.

What alternatives have you considered?
A clear and concise description of any alternative solutions or features you've considered.

Do you have any additional context?
Add any other context or screenshots about the feature request here.