Full list of all 56 Tales of Zestiria achievements. It takes around 100-120 hours to unlock all of the achievements in the base game on Windows.
The base game contains 50 achievements, and there is 1 DLC pack containing 6 achievements.
This is proof that you've completed all the extra dungeons at difficulty level Normal or above. But further challengers await you, in places you've been and places you have yet to be.