Can we change the reference table in a reference variable, based on a select box variable's value?

[yashkamde]

No, it is not possible at runtime..

If my respons helped mark as helpful and accept the solution.

[Brad Bowman]

A workaround to this that I have used is to create 'duplicate' variables - one for each table that could be needed in this scenario.  Then you can have a UI Policy or Client Script that shows only the correct one based on the select box value.  Makes it a bit trickier if a flow or reporting depends on this variable, but there are some things that can be done to make that more straightforward too.