I'd been having problems with the scale of the VLC interface at 4K on my Linux machine (KDE Plasma, Wayland).
I found a solution from a mix of previous solutions for Windows and other Linux solutions which did not work for me. The problem is with QT (which is used by VLC) and the linux solution was to put extra lines in the /etc/environment file but I found while this fixed VLC it mucked up all other QT apps including my Plasma desktop.
The solution is to use VLC flatpak and set the environment variables for the VLC flatpak app only using Flatseal or the Flatpak Permission Settings in KDE.
Add two Environment variable:
Variable name: QT_AUTO_SCREEN_SCALE_FACTOR
Variable value: 0
Variable name: QT_SCREEN_SCALE_FACTORS
Variable value: 2
For the second variable, scale_factors, set it to match the scaling you use on your desktop. 1.0 means 100%, 1.5 is 150%, 2 is 200% and so on. My desktop is set to 225% scaling, so I set mine to 2.25 and it worked. In the end I went up to 3 for VLC because I liked the interface even more at that scale (it's a living room TV Linux machine)
Hopefully this will help other people using VLC in Linux.
If you don't want to use Flatpak, you can add the same variables to your /etc/environment file (in the format QT_AUTO_SCREEN_SCALE_FACTOR=0) but be warned you may get jank elsewhere. This may be less problematic outside of KDE Plasma as that is QT based desktop environment. For Windows users it is a similar problem with QT and there are posts out there about where to put the exact same variables to fix the problem.
The reality is what youre asking for is very complex - you're asking for lagless streaming for a desktop. That is running a GUI on remote hardware, and then streaming that video to another computer with low latency so you have no perception of lag in moving the mouseor interaction, and continuous streaming of desktop updates.
There are lots of factors at play that can make it a poor experience.
You can have what you want if:
Its very hard to achieve all those things even when youre creating machines that are dedicated for remote desktop streaming. I have done that in my work with Windows devices and to get good quality streaming we needed dedicated hardware, dedicated software and high quality internet. And even then some of our users had bad experiences.
Most remote servers are definitely not set up to provide what you want. Dedicated software for the task will help as there are lits of tricks that they apply to make a streaming desktop appear latency free versus simpler solutions that just stream the actual desktop.
VNC is not a good solution - its basically just taking screenshots and streaming those to you. It works with fast devices on a local network, but is very limited in your use.
If you really want to solve this look at software optimised for low latency uses such as gaming. For example Moonlight/Sunshine are for game streaming but work with desktops. They are designed to be low latency high quality. But to achieve that you need the video hardware on your server, and the good low latency stable internet connection.
Real world high quality desktop streaming also needs good graphics hardware and optimised tools. It can be achieved with open source software but you need the hardware to to do the heavy lifting.