Hi, @Asad Ali Khan.
Yes, connecting an account to online banking saves you time from manually adding transactions from the (+) New icon. However, transactions are only uploaded as income and expenses or payments and deposits. To track your inventory accordingly, I recommend recording purchases and sales to keep your on-hand value updated.
For more tips about handling your transactions and inventory items, I recommend checking out the topics from our help articles.
Moreover, here's an article you can read more about online banking connection: Connect your bank feeds using Open Banking.
On the other hand, here's how you can categorise and match online bank transactions in QuickBooks Online.
If you have any other questions about the online banking connection, please let me know by adding a comment below. I'm always here to help. Keep safe!