There's an area JUST northwest (like, no more than 20 steps away) of Camp Tranquil. It has a variety of monsters from level 16 - 29. The repop rate there is good and there aren't too many aggros to worry about. Great area to grind on for a small duo group. Mobs are squishy. Just be careful of the Canopy Galago's Dropkick (it executes quickly so more likely than not you WILL get hit by it) and be mindful of causing enemy mob links when you start leveling up.

Pre 1.19 I used this area to level all my unleveled classes to 20-22. Probably one of THE best areas to level in because of how accessible it is and the decent mob density.