The options in BitMaxz' screenshots will show regardless if that option is enabled or not.
As for the send tab, "Create Unsigned" will display in place of "Send" if the wallet is watch-only.
For the PSBT in the 'File' menu, those are available regardless of the option.

The true option that'll trigger with the option enabled is the "Create Unsigned" button during send confirmation.
Normally, a wallet can only send after the 3sec timeout, but with the option enabled, there'll be a "Create Unsigned Button" there as well.
Thus, there's a "PSBT control" instead of direct send.

Here're the screenshots;
without "Enable PSBT Controls":

with "Enable PSBT Controls":



Reference:
github.com/bitcoinknots/bitcoin/blob/29.x-knots/src/qt/sendcoinsdialog.cpp#L352