Will Swiss Airlines provide vouchers for a booking I cancel?

Nowhere on the email receipt from Swiss Airlines does it state anything about the tickets being non-refundable, nor does it state anything about cancellation policy. It does state the flight is Operated by Edelweiss Air.

Impossible to say based on the information you provided. You are going to need to call and speak with them.

Virtually all airlines sell multiple kinds of tickets. Some tickets are fully refundable (you typically pay more for those). Some are completely non-refundable (surprise, those are the cheapest, and surprise again, those are also the most popular with consumers, since most consumers only look at one thing when shopping for a flight: the lowest possible price). Some tickets are partially refundable (there are often different levels of refundability). There can also be variations depending on who canceled, when, and why.

In your receipt, look for something cryptic that says "fare class" or has a similar term. Read all the teeny tiny print. The answer may be buried there (very likely it's actually somewhere on their website, but you may not have found it or recognized it; websites can be infinitely large and make searching a challenge).

Bottom line, you will need to speak with someone at the airline -- experiences shared by other travelers probably won't help you much (because you and they may have bought different kinds of tickets, so their experience doesn't necessarily represent what yours will be).

I just went through the process of looking into the same flight and was offered "Economy Classic" (with "refund not possible" clearly stated) and "Economy Flex" ("refundable, except 80 CHF"). The latter is 30CHF more expensive. The former is the airlines "recommended" choice as stated next to the ticket price. Was I supposed to read "refund not possible" to mean "no cash refund nor flight voucher"?

Thanks for the responses. I will try to speak to a human...quite a task in itself!

Was I supposed to read "refund not possible" to mean "no cash refund
nor flight voucher"?

Unfortunately, yes -- that does seem pretty clear to me. Reinforces the old adage to "think before you click."

This was a tough lesson to learn. I hope you still asked the airline, just in case……

In late July I contacted Swiss Airlines and requested vouchers for the 382 CHF cost of the two tickets. Today (16 August) I received their reply: "While we understand that traveling can be challenging in these times and while SWISS has offered extensive goodwill policies in the past, we unfortunately must deny your claim." The full message suggests the airline cannot afford the financial burden of issuing vouchers, and asks for my understanding. Nevertheless, they do "hope to have the pleasure of serving [me] soon again."

Yes, it sounds like the above-referenced think before you click applies here. I find Google flights is very good about starting out with a range of fares and then defining what you do and don't get when you start clicking on them. There is no such thing as just a "plane ticket" anymore and as far as the airlines are concerned, the COVID goodwill period is long gone. They're too busy scheduling flights they can't hope to execute and counting their money.