It seems that there isn't a plugin to perform the right-hand-rule on a layer or selected features. Can this be done by using some Python code? Is there a function that works in the same way as ST_ForceRHR?
Since QGIS 3.4.3 there is
QgsGeometry().forceRHR() as Python equivalent. You can use it as follows:
polygons = QgsProject.instance().mapLayersByName('polygon') with edit(polygons): for feature in polygons.getFeatures(): rhrgeom = feature.geometry().forceRHR() # forceRHR() returns a geometry feature.setGeometry(rhrgeom) # To actually change the geometry, use setGeometry polygons.updateFeature(feature) # Dont forget to "save" these changes