TLDR: If you are a heavy Matlab user and you like to use external monitors with your Windows laptop, DO NOT buy a 4k laptop. You will regret it.
Longer story: I am currently using R2019B on a Microsoft surface book 2 with 4k display, along with two external monitors with 1920x1200 resolution, on Windows 10. It is an absolute nightmare. You can either run Matlab on the laptop with no external monitors, or run it on the external monitors in clamshell mode (laptop case closed) - having all three screens is essentially totally unusable. Among the many problems: Depending on which screen Matlab starts on, the windows may be tiny or huge, or start completely off-screen; some things are really hard to click in 4k because they are pixel based; copying figures sometimes only copies a tiny portion of the figure, and other times creates a tiny copy of the whole figure; font sizes and line widths often get screwed up when converting Office documents to pdf. I have been a Matlab user for over a decade now, and this current setup is the worst performance I have had (which is saying a lot, given the many rendering bugs which Mathworks was seemingly unable to fix in the 2011-2014 time frame). Using Windows with a 4k laptop is bad enough, but Matlab's performance is substantially worse than any other app I use.