As a new feature in ArcGIS Pro, Pro supports "Clause" mode for SQL expression type parameters in tools and other parts of the interface like the Definition Query of layers, and even defaults to using "Clause" mode.
However, for advanced users with SQL knowledge, that may wish to exclusively use SQL mode, there is no option at all to switch the default from "Clause" to "SQL", meaning the user needs to manually switch each time an expression is displayed in the user interface.
It would be highly desirable to have an application wide setting via the "Options / customize" dialog of Pro to allow users to switch to "SQL" mode exclusively throughout the entire application.