You can make use of a classic activity called ‘Path Exists’ using this you can check whether the file is there or not. This activity returns True if the Input Path exists, False if not. This Boolean output you can use further to check in if condition or in a way you want to configure.
Not knowing where a file’s location is before you search for it does make things more difficult which I would try to avoid. I think I would do something like this if you really can’t be sure:
What I do here is go through all the files in the folder and check if the filename matches what I expect. Make sure to set the “Include subfolders” property.
This does involve you having to split out the folder & the filename on the queue or you will have to use some string manipulation here to seperate out the filename & folder from the path.