most likely you'll be able to do it but before doing it you'll need to consider a couple of things
1- your laptop is premium, true, but its a little dated today ( resale value 500$ to 700$ ).. the 4k panel inst exactly cheap ( you might need to change the entire top lid assembly )
2- 4k panel will be nice but its glossy ( eye strain wont be an issue ? )
3- your laptop needs a new battery by now ? putting a expensive 4k panel on laptop with a almost dead battery , thats another 100$- 150$ ?
4- the 4k screen will munch through your battery much quicker than a 1080p screen .. no problem?
5- the difference between a 1080p and a traditional hd 1366 * 768 is a lot - but between 1080p and 4k the difference wont be as day and night if you ask me
6- xps 9550 was a new design and had many issues - ( I had the 4k version and the motherboard went toast - sold it on facebook marketplace for 250$ CAD for parts )
in my humble opinion you might just want to sell the one you currently have and add a 200$ to 300$ and if you get lucky you can buy a used 4k laptop like the hp spectre x360 or envy x360 or dell xps 15 9560 4k for a reasonable price on facebook marketplace or kijiji or craigslis ( ebay tends to be more expensive for some reason )