import os
local_dir = r"J:\gp190225\Home\.qgis3\profiles\default\python\plugins\pegelonline"
lyr = iface.activeLayer()
lyr.loadNamedStyle(os.path.join(local_dir, "styles/trend.qml"))
if iface.mapCanvas().isCachingEnabled():
    lyr.triggerRepaint()
else:
    iface.mapCanvas().refresh()