Do you support 48 kHz upsampling?

Yes. Support depends on the model. UniverSR, AudioSR, and FlashSR upscale low resolution audio to 48 kHz (super resolution). The 'Music Upscaler' restoration algorithm keeps 48 kHz sources at 48 kHz, and restores 44.1 kHz-or-lower sources at 44.1 kHz.

For the model-level details, read the UniverSR sample-rate guide or compare models in the restoration docs.