As shown in the public information here, it is currently not possible to control file type columns with business rules.

//Types of columns

URL: https://docs.microsoft.com/en-us/powerapps/maker/data-platform/types-of-fields#file-columns

//Create a business rule for a table

URL: https://docs.microsoft.com/en-us/powerapps/maker/data-platform/data-platform-create-business-rule#column-type-support-with-business-rules

However, we have received inquiries from customers who want to control file type columns with business rules.

For example, being able to set a condition in a business rule and upload a file by satisfying the condition will improve business efficiency.

We believe that by realizing this feature, it will be able to improve the functionality of Dynamics products, so we would appreciate your consideration.