leveling jobs after 70 without a PotD / HoH type thing is... awkward. You basically do the roulettes and the pixie dailies, maybe also the Stormblood beast dailies if you really want to, all of which takes what, 1 hour, 2 hours? You gt your level, level and a half worth of xp from that, then you kinda just awkwardly stay at whatever level you landed and realistically park the job until the next day. I guess you can run random dungeons or fates but nah.
Like I said, it's just awkward not having the traditional alt class that would just go through the same old quests.