How do you add Variance and VariancePercent functions for an ASO cube

Are calculation functions like Variance and VariancePercent supported in ASO? I cannot locate good Oracle documentation and the AI search results contradict themselves (some results show MDX can be used but in testing still producing errors).

Reporting for EPM Cloud is currently using Variance and Variance % calculations but I'd like to centralize these calculations as members in the Scenario Dimension to compare Actual to Budget and Forecast.

Appreciate any insight on first whether this is possible (or do these need to be setup in the BSO cube) and second, what is the MDX syntax or other if supported in ASO