I am using a kind of customized imageryProvider based on this sourcecode
https://github.com/TerriaJS/terriajs/blob/master/lib/Map/MapboxVectorTileImageryProvider.js
I have two options. either change the url or change the stylefunction. I think they both will effect the newly loaded tiles but I think there must be a way to re render the already downloaded tiles as well otherwise there will be a miss match between the already loaded tiles and new tiles.