I've made a generic script to load from CSV any XYZ tiles

It's more generic than the one by Klas Karlsson (not hardcoded content) but you will need to set additional layers on your own as the default CSV provided does not contain a lot of default basemaps.

You should also be aware that soon QuickMapServices, an alternative plugin to QGIS OpenLayers plugin, will be compatible with QGIS 3.0 as there was a successful crowdfunding campaign for QuickMapServices http://nextgis.com/qms-plugin-crowdfunding/

I've made a generic script to load from CSV any XYZ tiles

It's more generic than the one by Klas Karlsson (not hardcoded content) but you will need to set additional layers on your own as the default CSV provided does not contain a lot of default basemaps.

QuickMapServices, an alternative plugin to QGIS OpenLayers plugin, is now compatible with QGIS 2.x & 3.0 as stated in this blog post announcement