Starting work in Switzerland and surprised by a very minimal contract. Normal practice or huge red flag?

There are other documents, employment policies and guide(s) that will be referred to, or included in the contract.

As I have just ended a 20 year contract with a Swiss company I can promise you that... I have the original contract, various contract extensions and overtime agreements, but there are the extra details like hours, Dress code, holidays, pension agreements, tax details including dependants etc which all come into play.

Just ask the HR representative for the other bits, easy. Any legit company will make sure you have all your questions answered.

I am employed in Germany, not Switzerland, but as far as I know, the situation is similar.

I would not expect any information about holidays, sick leave, pensions etc. in a work contract, because all this is determined by law. No employer can decide about the number of holidays or the way sick leave is dealt with, they just have to stick to the law. The same applies to the pension insurances; there are rules how much has to be paid for every employee. There is nothing to decide or discuss.

So I would not consider it a red flag, not at all. When you start your new job, just ask your colleagues / boss / HR about the number of holidays and everything else you want to know.