Easiest way to make npc's that walk around?

Hello! I'm building a small 3d tycoon style game and I wanted to add characters that I could program to walk to specific points on a grid.

Some of the unity tutorials (https://learn.unity.com/tutorial/interactive-tutorials-introductory-lessons) have a prefab and some code that create little walking npc's that use navmesh and navmesh agents.

Is there a simple partially built prefab that's easiest to use to drop characters, animations, and navmesh systems into a grid? Or is this something that's best to build from scratch by figuring out to write code for the navmesh system and coding it for 3d models and setting their animations?

Also, does the navmesh system include a lot of pathfinding automatically, or is this something I need to learn to write?

Thanks so much for your time!

 

I learned from this vid.... all my AI are kinda based off this