Potentially - it depends on the implementation, how it is used and, of course, the system it is used in (there are no free lunches, after all). It does, however, provide an alternative means of getting your digital source signal into your DAC which may, or may not be beneficial depending both on your DAC, source and the DDC in question.
If you invest in a good DDC, with proper isolation, excellent clocks/clock stability, no power/noise issues, then the benefits tend to be realizable across DACs. Not necessarily ALL DACs of course … nothing stops a DAC design putting a better USB->I2S* implementation in their own box than the DDC you happen to be using
For example, prior to the Unison interface, Schiit’s Yggdrasil generally sounded better driven via AES than it did via USB. USB Gen 5 muddied that somewhat, depending on source system. So a good DDC (e.g. a Mutec unit or a Singxer SU-1) could let you use a source with only USB as an output option with the AES input on Yggdrasil.
Similarly, the original versions of the Holo Audio Spring DAC sounded best driven via I2S. A DDC (or suitable transport) is necessary to use that interface.
Bifrost 2? If you have ground-loop issues it may make a difference vs. the native Unison interface, but that’d be dependent on the quality of the TOSLINK implementation, and cable, AND DDC vs. the already excellent Unison input. You’d be looking at spending $400 or so on the DDC and another $100 on a proper Lifatec TOSLINK cable to get something that had any chance of being equal.
*Interally, DACs generally use I2S for data transfer … specifically the DAC chips.