NOTE: Please only use the following as a reference and get the part number checked somewhere to ensure it's correct before purchasing anything as I don't know for certain.I had floating discs on my S3 Competizione 180hp. My 70th Esseesse, like the current Competizione, has non-floating 305x28mm's. I'm not sure the exact point they switched to non-floating, but given the 2016 I'm thinking introduction of Series 4.
When I Google "abarth part number competizione front disc" in UK, I can get the same site as posted above but with a different link (
https://www.partsworld-uk.com/products/brake-disc-front-500-abarth-competizione-2016). The Google results page suggest a part number of 52041114 but it doesn't show on the page when I go into the link.
Several sites list this part number, one of which was moparstore.co.uk, apparently "THE OFFICIAL STORE FOR ACCESSORIES, PARTS AND SERVICES FOR FCA VEHICLES". If thats the case there must be a German version, and there is,
https://moparstore.de/catalogsearch/result/?q=52041114. You can get it to filter by number plate but that doesn't work for me on UK site, shows no results. Haven't tried by VIN. Each item has technical specs section at the bottom and these show as 305mm.
Also using Google, searching for the above part number along with site:*.de to limit it to any website ending in .de bring up some more results at cheaper prices. Again not being familiar with German car parts stores, I don't know how good any of these are.
I would get onto dealership or Abarth Customer Service/Head Office to get them to tell you the actual part numbers.