lightning network – How do I send the change output from an input to fundchannel to a taproot address instead of to a SegWit v.0 address?

The documentation of the fundchannel command does not appear to make any references to parameters for setting the addresstype for the change output of a funding transaction.

However, according to the announcement of Core Lightning 23.08

We also added Taproot address support, thanks to Greg Sanders: you can issue Taproot addresses for people to send you on-chain funds, and we will immediately use them for our own change outputs. Taproot addresses (i.e., P2TR) start with bc1p instead of bc1q, just so you know!

and the Core Lightning 23.08 Changelog, Core Lightning should generally be creating P2TR change outputs since version 23.08 after pull request #6035 added Taproot wallet support.

If you are running an older version, you should hopefully see the desired behavior after upgrading. If you are running version 23.08 or later and your funding transactions do not have P2TR change outputs, you might want to report a bug to the Core Lightning developers.