The Linux’s display system, uses multiple technology, protocols, extensions, applications, servers (daemon), drivers and concepts to achieve the windowing system for instance: Xorg, Wayland, X11, OpenGL, RandR, XrandR, Screen Resolution, DPI, Display server, etc. This can be overwhelming to understand fully, but each side of it is meant for a specific purpose and they are not used all together at the same time.
On most desktops system (like KDE or Gnome) there are settings available on their respective settings panel, this guide is for additional/manual settings that can be applied to scale an application or the whole desktop. This reference article have many valuable informations for the matter.
How to configure and secure a VNC server on Linux with TigerVNC? (on a screen less server or a classic machine)
Since the VNC Server (TigerVNC) configuration is the same on most Linux distributions and only the installation method differ, this wiki is targeting: OpenSUSE, Fedora, CentOS, RHEL, Debian, Mageia, Void Linux, Arch Linux, Manjaro and FreeBSD (in order to be useful for more people)
Installing a VNC Server
On Linux (on a classic machine or a screen less server) there are multiple (opensource) possibility for a VNC server such as TightVNC, TigerVNC and TurboVNC (this is a non exhaustive list, this guide will be using the native version of TigerVNC):
Google cloud services (computing instance) offer encryption by default for disk storage, the customer can provide its own key with the feature customer supplied encryption (detailed here also).
How can we apply a disk encryption with cryptsetup without giving the encryption key to google?
On Linux, when using an encrypted disk (luks), it is unlocked at boot time with a password the idea here is to encrypt the disk with cryptsetup on top of the google system (default encryption) and get an earlier access to the instance to be able to unlock the drive at the boot time. This can be implemented with the help of the remote serial console feature (note that an opensuse VM was used for this howto, the different steps should not differ for other distros).
When targeting a true full system backup, disk image backup (as required for this investigation) offer substantial advantage (detailed bellow) compared to files based backup.
With files based backup disk/partition structure is not saved; Most of the time for a full restore, the process is a huge time consumer in fact many time consuming steps (like system reinstall) are required; and finally backing up installed applications can be tricky; Image disk backup avoid all these cons and restore process is a one shot step.