The only way to do this is with an automation & integration tool like Make.com. (There are other automation & integration tools as well, but Make is the one that I recommend for my clients.)
Your users would put the CSV file (or the XLSX) file into a “watch folder” in a cloud storage space such as Google Drive, and then Make would process the files that are dropped into this “watch folder”.
I would recommend using CSV files instead of XLSX files, because Make already has a Parse CSV module built into the app, whereas you would need to custom-create your own way to parse your XLSX files.
Note that all of your CSV files will need to share the same structure in order to work properly. If you’re expecting different structures, then one easy way to handle that would be to setup different watch folders + different Make scenarios to process each watch folder.
p.s. If it’s your very first time working with Make, it might take a little while to figure it out. If you have a budget for your project and you’d like to hire an expert Airtable consultant to help you with this, please feel free to contact me through my website: Airtable consultant — ScottWorld