If you only want to visually hide the points outside the polygons, but still keep them, simply click next to Enably symbol layer to data driven override icon > Edit... and insert this expression: overlay_within ('polygons') and replace polygons with the name of your polygon layer.

All points outside the polygons visually disappear, but are still there in the attribute table.

If you only want to visually hide the points outside the polygons, but still keep them, simply click next to Enably symbol layer to data driven override (list) icon ɛ > Edit... and insert this expression: overlay_within ('polygons') and replace polygons with the name of your polygon layer.

All points outside the polygons visually disappear, but are still there in the attribute table.

Screenshot (click to enlarge): above, only points inside a polygon are shown, based on the expression; compare with the image below, same layer, but this time with no data driven override for Enable symbol layer: