At 98 you have the option to drop what you're doing and return to your capitol city to start the quest for your Legion Artifact weapon. However, I do not believe this is necessary to do right away unless you're struggling with kill speed in your current gear. I would recommend waiting for a natural pause, such as hearthing to repair and clear your bags. From 100 to 107 you won't even really fight mobs that often; only just enough to clear the way to any treasure you need to pick up.
World of Warcraft: Battle for Azeroth focuses on the rivalry between the two most important factions of Azeroth, the Alliance and the Horde. The expansion adds two new continents (Zandalar and Kul TIras), divided into islands, where you can find new dungeons and raids, quests and previously unseen enemies, as well as six new playable races. Once again, the maximum experience level of the player characters increases (from 110 to 120). Battle for Azeroth also introduces two new game modes. In the first one, groups of three characters explore chosen maps and fight randomly assigned monsters and threats. In the other mode, groups of twenty characters each try to take over locations in strategic places for their factions.