Hello there, SSLD.
If you're referring to the form, you can adjust the logo size to a small one. When printing the form or document, it'll show as small. Here's how:
Here's a sample screenshot for additional reference:
Also, customizing templates or forms focus on the design and appearance of your sales forms. For details, please check out these articles below:
Customise invoices, estimates, and sales receipts in QuickBooks Online.
If you're referring to something else, please go back to this thread and let me know by commenting below. Take care and stay safe always.