There are lots of Lightroom presets that you can download from the web and use in the program. The question then becomes where do you put these. There are a couple of ways to find the presets folder in Lightroom. One is to open the Develop module, locate the presets dropdown list and right-click one of the user presets that you’ve created and choose Show in Explorer. This opens the Lightroom presets folder inside Windows Explorer. If you’re using a Mac, the link will be to the Mac equivalent. The other method of doing this is to choose Edit > Preferences > Presets tab. Click the Show Lightroom Presets folder to view the presets folder location.
You will need this location to store downloaded presets, in and you will also need the location so that you can ensure that you back up your presets so that you do not lose them as, by default, they are not stored with the catalog and so will not be backed up with it.