I used to connect my MBP 2018 to the monitor LG 27UL850-W. In my old setup, I connected this usb-c port of the monitor to my MBP's usb-c port:
This connected both the audio/video signal and the power with just one cable! Very cool.
Now, with my MBP 16 2023, this can't be done anymore. So, I connect the monitor's usb-c to the MBP's mag safe 3 (just for the power supply) and I use a separate HDMI cable for the audio/video signal.
Although it seems working, I'm wondering if this setup is safe or if I'd better use the power adapter bundled with the MBP 16 2023 (I do not now if I'm going to miss or break something without it).