For individual variations and for listings without configured variations that have individual inventories, once the inventory level reaches 0, the listing will automatically be classified as “sold out”. The system will not send out any additional notification about this.
For listings with individual inventories configured for all variations, when the inventory level for any one of the variations reaches 0, its inventory level will be displayed in red. If the inventory levels for all the variations of a listing reach 0, then the listing will be automatically classified as “sold out”.
Under Listings, you can adjust the order in which your listings are displayed by selecting “Stock: low to high” to check which listings have low inventory levels.