Automatical Y Axis offset

Hello developers, i am currently making an NPCs movement system for a tower defense game, but i’ve ran into a problem.
As shown in the picture below, they are spawning underground:

image

While the intended position should be like this:

I’ve tried to calculate the offset manually through Vector3 values, but my question is, how would i be able to automatically set the correct Y offset without having to do this for every single NPC?

Here’s an example of what im currently doing, which is really tedious:

image

Is there any way of achieving this?

Im pretty sure if you find the total height of the model you can do y = y+(height/2)