Extremely high memory usage on DELL XPS 15 despite being brand new and running no programs

You did helpfully provide the screenshot of Task Manager showing the processes using the most memory. If you can eliminate some of those processes, you will free up the memory they are using. You certainly can go to Settings > Apps > Startup and disable some of the apps you're not using, like Teams, OneDrive, etc. You can also free up some memory by uninstalling Dell SupportAssist, though you would lose its functionality, and possibly miss alerts to install critical driver updates.

That answer is actually too pat. It's kind of a truism that unused memory is wasted memory. Many of those processes on the list are dormant most of the time, but if needed they can act immediately since they are resident in memory. If your system needs memory for a high-priority task, the least recently used tasks will get offloaded to make room. If the system is starved for memory it'll spend a lot of time copying memory images to and from secondary storage (your SSD) but you're not remotely close to that happening. I don't think you have a problem at all, but you can certainly take the actions above to maximize your available memory.

Uninstall all of the garbage Dell ships installed. It's ridiculous that RAM utilization is ~65% out of the box.

For comparison's sake, I have another laptop, also running Windows 11 with 16GB of RAM, and RAM utilization is ~20% at startup. Dell lost their way many years ago. If it wasn't work issued, I wouldn't be using a Dell.

Same problem did u find a solution?

I also have the same problem, the issue's a lot bigger than just processes. My computer also had really high memory usage despite only having a browser on. You should check Task Manger -> Performance -> Memory, where they show items in more detail. It's NOT normal that you're using 60% of your memory with only one browser task (1.2 GBs).

For my computer, I noticed that the Non-Paged Pool section was 1.2 GBs, which is really high. So I went into Task Manger -> Details, where they show processes in detail. You can right click one of the column headers and click "Select Columns", and then select the information you want. For me, I chose "NP-pool" because it was abnormally high. And here's where things get weird. So, all my processes have only ~1 MB of memory used on the NP Pool. So yeah, there's a memory leak, and it's coming from the kernel. Probably a driver or some weird stuff. So I went and checked PoolMon, and turns out Intel's "ismc" is causing memory leaks. There are posts on the intel forum contacting tech support about it,  but Intel wasn't able to replicate the problem, so it remained unsolved. The typical solutions would be to update drivers and the such, but that didn't work as well. Another culprit is etwb, which is window's logger. I don't know what to do about that one honestly. 

TLDR; I also use an XPS15 and have abnormally high RAM usage despite doing low load tasks. For my case, it was a memory leak issue with Intel's "ismc" storage technology, and Window's "etwb" logging. Intel wasn't able to replicate the problem, suggesting that the issue is only present in certain builds. So yeah, you might have an unsolvable memory leak going on