Touchscreen (DSI) + HDMI simultaneously?

I have Volumio on a Raspberry Pi 4 with the official 7" touchscreen connected via the DSI ribbon cable port. I would like to add the ability to also view the album art etc on my 4k TV via HDMI, but I’m unable to get a signal from the HDMI port 0. Is it possible to have the video output from both the DSI and the HDMI simultaneously? I guess there may be issues around resolution so a simple screen duplication may not be possible.

Volumio 3.661
Touch Display plugin 3.4.0