Dear Carley Stephens
Good day!
No, when you share a file, you can see that there is a separate option to disable downloads, which means that even if the user only has read-only access, he can still download the file

If you want to prevent users from downloading files by default, you may need to use PowerShell, please kindly check this article: Block downloads for view-only files in SharePoint and OneDrive - Microsoft Support



You could also set a policy to block all downloads and exempting users with the code in the following article:
Block the download of files from a SharePoint site or OneDrive (preview) - SharePoint in Microsoft 365 | Microsoft Learn.

Meanwhile, considering we mainly focus on general and build-in queries in SharePoint Online, we may have limited resource about PowerShell script.
At the same time, considering we have a dedicated channel SharePoint Development - Microsoft Q&A, for you to be assisted properly, we sincerely recommend you go to that community and post a new thread, members and engineers over there are proficient in the knowledge of PowerShell scripts and SharePoint customization queries. They will focus on the specific situation on your side and share specific suggestions. We are sure that our experts from that team can address your query effectively and accurately.
Sincerely,
Tin