Will I get a WhatsApp when an ingredient goes below its par level, like I do for a dish?

Not today. The WhatsApp warning belongs to dish counts: set an alert level on Menu → Inventory and your managers group is told once when the count drops past it. Ingredients work differently. A par level makes the ingredient show as low on Ingredients & suppliers, the Short line at the top names everything under par, and the Reorder column says how much to buy. Nothing is sent. So for restaurant stock control the habit is to open that page before you order, and to count a dish rather than an ingredient when you need the phone to buzz. The Stock, recipes and suppliers tab in the docs says which half does what.