S3 Wasabi filter upload files extension

Question

I want to check am I right in understanding of policies to S3(wasabi). Below are my policies

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": "s3:*",
      "Resource": [
        "arn:aws:s3:::testing-files/*.pptx",
        "arn:aws:s3:::testing-files/*.png",
        "arn:aws:s3:::testing-files/*.zip"
      ],
      "Principal": "*"
    },
    {
      "Effect": "Deny",
      "Action": "s3:*",
      "Resource": [
        "arn:aws:s3:::testing-files/*.txt",
        "arn:aws:s3:::testing-files/*.csv"
      ],
      "Principal": "*"
    }
  ]
}

I want to filter my uploading files by extensions. So these are my things I want to check:

1. Defined policy in my bucket in wasabi or in AWS S3 override global policies or not?
2. First statement with allow effect allow to upload only that given extensions on my testing-files bucket and denay others extensions to upload so I can omit second statement?
3. "Principal": "*" means for all users defined in my wasabi/s3 users? So it is encapsulated not access for public?

And last am I do it right or should find in wasabi option to set it(I can't find it)?