Will my plan be upgraded automatically once I use up my included returns quota?

Understand Rich Commerce billing and plan upgrades. Learn about return quota usage and plan upgrades. Manual plan upgrades or additional return payments available.
No. The way Shopify has built their Billing for Apps is that only the Store Owner can approve a new subscription.
After you have exhausted your included monthly quota additional returns are billed per return ("Usage Charge") until the Usage-Charge Limit of your Shopify Account is used up. A notification in the Rich Returns' Dashboard will provide you more information on this . In your Rich Returns' Dashboard navigate to Account / Your Plan / and check your current return usage quota. The dashboard will also tell you what additional returns are billed at.