Descent text will assign a downward offset attribute to the text (Only for texts, not for images. If you want to make images lower, you should set "ascent" property to a lower value)
# %nameplates_descent_{0}%
descent-text:
player:
text: "%player_name%"
descent: 5 # This value should be no lower than 0
is-unicode: false # If you characters can't show correctly, enable this and reload the resource pack