Discrete Graphics in Latitude?

It depends on what you're looking for.  The only remaining systems with true, discrete graphics are the high-end Precision and Alienware models.

The Latitude models come with hybrid video (the "discrete" GPU boosts the Intel GPU, but CANNOT run independently of it).  If that's what you're looking for, most Latitudes except for the very low end models have it at least as an option.

Most Latitude models have a TPM when they're sold in a location that permits it -- not all sales markets allow TPMs, though.

To expand on ejn63's post, the Precision 7000 Series models do have both discrete and integrated graphics, but they are special in that it's possible to disable the integrated graphics completely, either for all of the display outputs or for those plus the built-in panel.  You can also choose to run those models in the more common mode that ejn63 called "hybrid video".  This flexibility is possible on those models because they use a more expensive and complicated motherboard design that allows the discrete GPU to take direct control of those outputs instead of the Intel GPU.  But the vast majority of laptops on the market will operate only in that hybrid mode, with the discrete GPU operating as a render-only device.  This means that certain technologies that might be supported by the discrete GPU, such as 5K displays, VR, G-Sync, stereoscopic 3D, etc. will NOT work unless the integrated GPU also supports them, since the integrated GPU is always in the video path.

If that's not a concern for you, I believe the smallest non-Alienware system you can get that includes discrete graphics is a 15" model, such as the Latitude 5580.  To my knowledge, TPMs these days are standard on all systems except where prohibited by regulations, but check the spec sheet or Google around before purchasing to confirm.

One final note, if discrete graphics horsepower is important to you, you may want to look at something like the XPS 15 or its sister the Precision 5520.  They're not as powerful as the discrete graphics in the Precision 7000 Series, but they're also less expensive, thinner, lighter, less power-hungry, etc -- and they'll definitely be faster than what you'd find in a Latitude.  Both models include TPMs by default unless you're in a location that prohibits them.  The main difference between the XPS 15 and Precision 5520 is the GPU.  The Precision variant comes with a Quadro GPU that's great if you use applications that take advantage of their special capabilities, but if not, the XPS 15's GeForce GPU is actually newer and will therefore be noticeably faster for all situations that wouldn't take advantage of Quadro acceleration.  The Precision model is also more customizable, so you can get combinations that wouldn't be available on the XPS (e.g. 32GB of RAM, 1TB SSD, and a 1080p matte display), and you can also get the top-end Class 50 SSDs (equivalent to the Samsung 960 Evo), whereas the XPS models only come with Class 40 SSDs.

You can get ProSupport Plus on an XPS system as long as you order it through the business store.

The one caution and compromise - XPS is considered a consumer system and isn't eligible for Pro Gold support -- which Latitude and Precisions are.  If this is business-critical, there are decided advantages to having immediate service and support available.

One REALLY final note: Another advantage of the XPS over the Precision and Latitude models is that if you're pressed for time on getting this PC, you're far more likely to find the XPS 15 in retail locations than the other model lines.  I know the XPS 15 is sold in the Microsoft Store, for example, although potentially not in the exact configuration you'd want of course.

And another alternative would be an Inspiron Gaming series system, since they may include TPMs these days as well, but I haven't looked into that to confirm.  The higher-end versions (especially a 17" model) would outperform the XPS 15 and even get close to Alienware (without the extra cost of the flair) because their larger physical size and bigger, heavier AC adapter means more capacity for cooling and therefore higher-performance components.  They'd also be less likely to throttle under load, which is an issue on most if not all high-end slim and light laptops, including the XPS 15 -- but not the Precision 7000 Series models since they're not "slim and light".  The downside to the higher-end models of course is that their size, weight, and power requirements make them less convenient, including in ways you might not always consider.  For example, the XPS 15 can charge from a USB-C/Thunderbolt dock like the WD15 or TB16, and even (slowly) on a 60W USB-C travel charger, because that system is designed for a 130W power supply.  Systems designed to use 180W or 240W power supplies won't charge at all from a travel charger and can't even be charged from a USB-C/Thunderbolt dock.