In QuickBooks Online, the Sales by state report is currently unavailable. In the meantime, we can create a custom field and add the state from there. This will be added to the filters on the reports so you can generate a sales by state report.
Here's how:
Proceed to the Gear icon and choose Account and settings.
From the Sales tab, click the Sales form content section.
Toggle the Custom fields to turn it on and enter a custom field name in the field given.
Check the Internal and Public (optional). Click Save, then Done.
Once done, create a sales transaction as usual, and you'll see the custom field. Enter the state in it and save the transaction.
Then, I recommend to run the Sales by Customer Detail report. Then customize it by going to the Rows/columns drop-down. Choose the custom field you created. This will group the data by state.
For your reference, please see the screenshot below:
Additionally, you may also check out these articles below on how to add fields on your sales forms and memorize reports in QuickBooks: