It seems that Apple Final Cut Pro software supports import of .ari files Alexa and Amira digital camera recording devices and thus can process them and save in a new project (.fcp). As far as we know, this is the only way how you can perform ari to fcp conversion.
Convert ARRIRAW file to Final Cut Pro project.
We found one software available in the database for this conversion.
Apple macOS / Mac OS X software - convert ari to fcp on OS X
A professional video editing software from Apple
Convert from ari file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.