How do I add pathfinding cost to certain tiles only?

Im making a game where i do the map using tiles, and there are NPCs on it

I want to add so path cost to the grass tiles so the characters use the sidewalks and roads instead

How do i do this?

You can move grass tiles to a separate tilemap and add PF cost to it.

How to add different cost to different tiles in same tilemap?

This is not possible with the official PathFinding behavior. One object - one PF cost.

You can do this with the EasyStarJS addon.

But if you decide to use the official behavior, you'll need a second tilemap.

Or use an invisible helper object, loop through the main tilemap and create cost objects on top of every tile that is grass on start of layout.