I believe the Optus account portal has this information however I don't know how detailed this information is or how long its kept. There are a couple of posts that suggest contacting support and requesting this information. The live chat below or the chat feature in the Optus app might be the best option.
Last time I checked it was only the last 30 days available on MyAccount.
As Yeldarb advised, please chat with us for the usage that you're after 🙂