Can I use the charger while connect on USB-C monitor that charge at 65W

@mrweirdmusician  that works fine.  The system will automatically switch to the higher wattage power source.  Dell even tells people to do this when using certain Dell docks with certain Dell systems.  For example, the Dell TB16 dock can supply up to 130W to an attached system.  The TB16's documentation says that it is compatible with the Precision 7000 Series models, even though those systems require more than 130W -- and the way that works is that the TB16's documentation specifically tells users of those systems to keep both the dock and the system's AC adapter directly connected to the system in order to keep the system running properly by giving it access to a full power source.

Fyi as a general statement though, it probably doesn't matter here, but when asking technical questions like this, it's usually a good idea to provide more information.  In this case you provided your display model but never mentioned the laptop model you're using.

But if it really bothers you, then you could always get a USB-C to DisplayPort cable instead.  The only other capability you'd lose there is USB data traffic over the USB-C port, but if you don't have any USB devices plugged into the USB ports built into the display, then you don't need that anyway.

Hello @jphughan​ 
I'm using Dell Inspiron 7570, when i connect the laptop to a monitor upon starting my laptop a warning appears - Monitor provides only 60W power but my laptop demands 65W. I've opted to not charge laptop using monitor but still it charges.

i wanted to know if i can also use the original laptop charger along with the monitor USB c PD supply?

monitor is benq GW2875.