Hey @Cv_Gandhi - bulk operations don’t currently support our inventory management APIs, but you should be able to use InventorySetQuantities to update the stock levels of up to 250 inventory items in a single API call.
You may need to iterate through a few separate instances of that call if you need to update more than 250 inventory items, but this is the reccommended approach at the moment. There’s a bit more info here where some other devs were discussing this: