code: def layers_intersect(layer_a, layer_b):
      
      extent_a = layer_a.extent()
      extent_b = layer_b.extent()
      if layer_a.crs() != layer_b.crs():
          coord_transform = QgsCoordinateTransform(
              layer_a.crs(), layer_b.crs(), QgsProject.instance())
          extent_b = (coord_transform.transform(
              extent_b, QgsCoordinateTransform.ReverseTransform))
      return extent_a.intersects(extent_b)
docs: Check if extents of two layers intersect.
  
      :param layer_a: One of the two layers to test overlapping
      :type layer_a: QgsMapLayer
  
      :param layer_b: The second of the two layers to test overlapping
      :type layer_b: QgsMapLayer
  
      :returns: true if the layers intersect, false if they are disjoint
      :rtype: boolean