I have an old C-Permit that expires in 11 months time. I would like to get the credit card style permit, all the covid pass measures would require me to show it regularly. Carrying the old large paper style permit is always a headache.
You could just ask your Gemeinde if it's possible to "upgrade" - it might be possible with the same dates on it that your current permit has. If you are British, you'll have to have your biometrics taken.
But since you were here before Brexit EU rules apply. Photograph and signature. If you were non-EU it would be the whole caboodle: Photo, signature, fingerprint, inside leg measurements, lung capacity and heart rate, just like the Swiss on their ID cards/Passports.
You can't "renew" it (as in get a fresh card expiring in now+5 years) but you can always go to a police station and report your existing permit as lost / destroyed and you'll get a replacement one in the plastic card format. It'll most probably have an expiration date in 11 months so you'll need to renew it soon and pay the 60-90 CHF fee twice.
"3. What must UK nationals who already have a permit for Switzerland (short-stay, residence or cross-border commuter permit) now do ?
UK nationals living in Switzerland who obtain a short- or long-stay residence permit before 31 December 2020 and are therefore officially registered in a local commune do not generally need to take any action. The same applies to persons with an EU/EFTA cross-border commuter permit.
However, UK nationals with a valid permit may be informed that they need to exchange their current permit for a different one. This will not affect their existing right to remain, as long as they continue to meet the relevant residence requirements under the AFMP. If they are not informed that they need a different permit, they must simply apply for a new permit before their existing one expires, as usual. After 31 December 2020, UK nationals will be issued with a biometric residence permit marked (in German, French and Italian) “In accordance with the CH-UK agreement of 25.02.2020”."