I'd like to perform a quick format on my external HDD through veracrypt but I'm not sure if a quick format will allow an outsider to download my data from the HDD with ease compared to a full format. I don't care if they see what it contains or whether it's encrypted or not, I just don't want anyone to be able to easily download files off of it. So is a quick format as secure—in terms of making it equally difficult for anyone attempting to steal my data—as a full format container?
Quick formatting a container in VeraCrypt does not make it "easier" for someone to access the files inside the container.In both cases, the container is encrypted and requires the correct password or key to be accessed.
The only difference between a quick format and a full format is that a quick format does not overwrite the data on the container with random data, whereas a full format does.
The VeraCrypt quick format documentation states:
It may be possible to tell how much data it contains (if the space was not filled with random data beforehand).
In simple terms, this means that a full format can take longer and may provide slightly better security against analysis, but in most cases, a quick format is sufficient.