Can any Laptop run 3 x QHD monitors with or without a dock?

@coys  If you do NOT plan on using the built-in display while you have 3 external displays connected AND you will be using Windows rather than Linux, then lots of systems can run 3x QHD.  The reason Windows vs. Linux matters is that most systems have the Intel GPU controlling all display outputs, including many systems that also have a discrete GPU, and Intel GPUs today are limited to 3 simultaneous independent displays total.  The issue is that on Linux, it isn't possible to completely disable the built-in display, so it always counts toward your 3, even with the lid closed.  But on Windows, the built-in display can be disabled even if the lid is open.

In terms of how you'd do this, there are a variety of options.  A system with Thunderbolt 3 paired with a Thunderbolt 3 dock would allow you to run all 3 QHD displays from the dock, although with some docks there might be requirements about the specific combination of outputs you can use.  Dell's WD19TB works this way for example, and the outputs you can use for 3x QHD depend on whether your source system supports DisplayPort 1.2 or 1.4 over USB-C/TB3.  It's spelled out in the manual.  If you don't want to go that route, you could use a USB-C MST hub or displays that support daisy chaining in order to connect two displays to a single output, and then another USB-C port or an HDMI output to connect the third.

@coys  Happy to help.  To answer your questions:

Yes, everything I described above assumes the standard 60 Hz refresh rate.

DP 1.4 is newer than DP 1.2 and offers more bandwidth, which can be handy, but when dealing with a Thunderbolt 3 system, DP 1.4 doesn't actually get you much more bandwidth than DP 1.2 due to how DisplayPort bandwidth works and the bandwidth limits of Thunderbolt 3 itself.  I can get into the gory details if you really want to know, but it really doesn't matter for your use case.  And most systems on the market today still only support DP 1.2/HBR2 because most Intel GPUs on the market today still only support DP 1.2.  The exceptions are the GPUs built into Intel's newer Ice Lake and Tiger Lake architectures, which are SOME of the Core 10th Gen CPU models and at least some Core 11th Gen CPU models, respectively.  But there are also Core 10th Gen CPUs that use an older GPU.  But again, if you get a system and dock that both support Thunderbolt 3, you will be able to run triple QHD.  At that point the only reason DP 1.2 vs 1.4 comes into play in the specific case of the WD19TB is that it changes the combination of outputs you can use.  With a DP 1.2 system, one of the displays will have to be connected via the "downstream TB3" port at the edge of the dock.  You can use something like a USB-C to DP cable to make that connection if the display doesn't natively support USB-C.  The other two can be connected to any other two outputs (except HDMI + the USB-C port near it, a combination that is never allowed on the WD19TB; only one of those can be used at a time).  With a DP 1.4 system, you can use any three outputs you want, again except HDMI+USB-C.

Office work wouldn't benefit from a discrete GPU unless your office work involves things like animation, video editing/rendering, or possibly machine learning type tasks that can be GPU-accelerated.

A laptop's internal display resolution has no bearing on its output capabilities to external displays.  This is a common misconception, and unfortunately one that I've seen Dell Sales/Support relay to their customers.  It is absolutely possible to have a 1080p built-in display and external 4K displays, for example.  But again, if you're running triple external displays, you won't be able to keep the built-in display active in that setup anyway.  Although that's not such a bad idea anyhow, since using displays that have very different pixel densities at the same time can introduce some issues of its own due to how Windows handles scenarios where multiple different display scale factors are in play at the same time.  For example, using a built-in 13" 4K display and an external 24" 1080p display at the same time is not going to be a great experience.  But that's a longer discussion.

@jphughan Thanks for taking the time to explain my options, its much appreciated 

I'm running windows so no issues there. A few more questions if you don't mind:-

Would all of these output to monitors at 60Hz? 

I assume DP1.4 is preferable to DP1.2?

Would I benefit from a laptop with a dedicated GPU in my mainly office work without any gaming?

Can a Laptop with a native resolution below QHD still output to external monitors at this resolution and at 60Hz?

Many thanks

@jphughan Awesome, thanks again.

Just need Dell to offer some Black Friday discount now 

@jphughan If I opt for an XPS 15 or Precision for example with an Nvidia T1650i would I still be able to run the 3 x QHD or does that functionality require connection to the intel board with no additional GPU?

Thanks

Thanks again for your help @jphughan .

I understood from your previous reply that it is possible to connect to an intel based laptop without discrete GPU but am trying to understand if it would still work with an Nvidia 1650 Ti for example?

I ask because my previous desktop wouldn't support the connections on the motherboard display ports without disabling the GPU.

Kind regards