It's possible to use SQL in field calculations for non-versioned enterprise geodatabases:
Calculate Field (Data Management)
SQL expressions support faster calculations for feature services and enterprise geodatabases. Instead of performing calculations one feature or row at a time, a single request is sent to the server or database, resulting in faster calculations.
Only feature services and enterprise geodatabases support SQL expressions. For other formats, use Python or Arcade expressions.
Out of curiosity, what are some examples of SQL expressions you use as field calculations?
I only have ArcGIS Pro 2.6.8 which doesn't seem to support SQL field calculations on enterprise geodatabases. So I can't test and am curious what's possible.
A simple point-in-polygon intersect update statement is faster at the RDBMS level. Note: this assumes and requires that the data have the same SRID.
UPDATE SourceTable
SET s.ColumnA = t.ColumnB
FROM SourceTable s
JOIN TargetTable t
ON s.Shape.STIntersects(t.Shape)=1