Thunderbolt 2 MacPro port to 49 inch LG monitor USB-C port

Update: No, the Thunderbolt 2 to DP adapter which I bought and connecting the 5K DP cable that came with the monitor, also did not work. I have tried many options now, including the ones suggested by Malcolm. But no success. The resolution cannot go above 3840x1080. I then searched online and found that there are other similar forums like https://discussions.apple.com/thread/250715148 where it is reported that after the Apple upgraded to Catalina, users cannot move beyond 3840x1080. Is it true? So waiting for the Apple to fix this bug and release an update to Catalina is the only option, for now ?? Please provide any inputs and suggestions. Thank you.

The monitor is 49BL95C-W and the USB-C on it says (Upstream SS). The description says it supports USB-C with 5210x1440 display. First, I tried the Thunderbolt 3 to Thunderbolt 2 adapter and the apple thunderbolt 2 cable, but it is simply not working. I have tried rebooting and other options. The monitor says "No signal". Then I bought the Mini DisplayPort to DisplayPort cable which is high-end (says support up to 8K). But the resolution I am getting is same to what I used to get with HDMI cable, means 3840x1080. The resolution quality is not good. Regarding audio, Yes, I tried the USB-A to USB-C cable today, but no, in the sound preferences under Input, I cannot see any device to control the sound from the keyboard or from the Mac sound preferences. Not sure what to do. Thinking of returning the monitor. One other option is: I ordered today a StarTech Thunderbolt 2 to DisplayPort adapter, and then will use the display port cable that came with the monitor. Maybe it improves the resolution from 3840x1080. Not sure. Any other advice would be really helpful. Thanks much.

Thanks Malcolm for your prompt reply. One issue by using mini display port to DP cable is that, it will not allow to control the sound or sound preferences from your keyboard. I have seen many discussions. For example, see here https://lifehacker.com/how-to-enable-mac-volume-control-for-hdmi-or-displaypor-1793607216. But some people mentioned that, Thunderbolt 2 to USB-C cable will allow the sound control as well. Not sure if it is true or not. Do they make Thunderbolt 2 to USB-C cables in 5K? Thanks much!