Hiding partially downloaded files

TL;DR: Technically the answer to your question is "Yes". Practically the answer is "No".

You can hide files by creating a .hidden file in the directory where you would like to not see certain files. The problem is that the .hidden file does not accept wildcards, so you cannot say *.part. Instead, you would have to have each individual file added to the .hidden file ... and this is per directory. So if your Torrents are going to multiple directories, you will need multiple .hidden files, each with their own list of specific files to exclude.

There are extensions you can add to Nautilus to build these files for you, such as Nautilus Hide¹, but the .hidden file is only read the first time you enter the directory. This means you would have to quit Nautilus and restart the application if you wanted to not see any .part files. This is anything but an ideal solution.

¹ the Nautilus Hide extension has been abandoned for several years and archived by its creator. I have no idea if this will work on modern versions of the Nautilus file manager or not. Caveat Emptor, and all that ...