Depends on the fab. KiCad exports separate drill files for plated and non plated so the fabs can use that to find out which holes to plate. But not all fabs have their toolchain setup to support this usecase.
Generally you might be interested in a few of our tutorials:
- Tutorial: How to make a symbol (KiCad v5.1.x)
- Tutorial: How to make a footprint in KiCad 5.1.x?
- Tutorial: Introduction to PCB design with KiCad version 5.1 (Getting Started)
And of course the FAQ: (Start Here) Frequently Asked Questions