Baking in blender

Right click > Add > Image Texture

In your image texture, click New >name it > double the suggested size to 2048 (depending on how complex, you may need to make it larger)

Switch to Edit Mode

Press A to select all the faces

Click UV > Smart UV Project

Change Island Margin to 0.08 so you don't have overlap and click unwrap

Switch to Object Mode

Swutch to your UV Editor

Browse image and select your image

Add yout image to every material (copy and paste)

Click on your render tab

Change your render engine to Cycles

Change your samples on both noise thresholds to 1

Scole down in your render tab to Bake and expand

Change the bake trype to diffuse

Uncheck your Direct and Indirect Lighting (contributions).

Click Bake

Save your image file with the word color in it

I created a folder on my desktop and saved it in the folder

Now switch the bake type to roughness

Change the color space to Non-Color and click bake

Save the roughness map that you just baked in the folder with the word rough in it

Now change the bake type to Normal and click bake

Save it with the word normal in it

Click on the shield then delete the materials

Create one material

Add the Node Wrangler Plug-in

Edit >Preferences > Node wRANGLER

With your Principled BSDF Selected 

Hold CTL + Shirt + T

Select the three maps you just baked