Fedora 30 : GIMP 2.10.14 with flatpak.

Flatpak is a software utility for software deployment and package management for Linux. It is advertised as offering a sandbox environment in which users can run application software in isolation from the rest of the system. see Wikipedia .
Flatpak builds available in i386, x86-64, ARM and AArch64.

[root@desk mythcat]# dnf install flatpak.x86_64 
Last metadata expiration check: 0:27:27 ago on Fri 01 Nov 2019 11:27:47 PM EET.
Dependencies resolved.
...
Installed:
  flatpak-1.4.3-1.fc30.x86_64                                                   
  p11-kit-server-0.23.16.1-1.fc30.x86_64                                        
  xdg-desktop-portal-1.4.2-1.fc30.x86_64                                        
  xdg-desktop-portal-gtk-1.4.0-1.fc30.x86_64                                    
  flatpak-selinux-1.4.3-1.fc30.x86_64                                           
  flatpak-session-helper-1.4.3-1.fc30.x86_64                                    
  ostree-libs-2019.4-3.fc30.x86_64                                              

Complete!

The install and run of last GIMP software is easy, see commands:

[mythcat@desk ~]$ flatpak install https://flathub.org/repo/appstream/org.gimp.GIMP.flatpakref

Note that the directories 

'/var/lib/flatpak/exports/share'
'/home/mythcat/.local/share/flatpak/exports/share'

are not in the search path set by the XDG_DATA_DIRS environment variable, so applications installed by 
Flatpak may not appear on your desktop until the session is restarted.

Required runtime for org.gimp.GIMP/x86_64/stable (runtime/org.gnome.Platform/x86_64/3.32) found in remote
 flathub
Do you want to install it? [Y/n]: Y       

org.gimp.GIMP permissions:
    ipc                   network        x11       file access [1]
    dbus access [2]       tags [3]

    [1] /tmp, host, xdg-config/GIMP, xdg-config/gtk-3.0
    [2] org.freedesktop.FileManager1, org.gtk.vfs, org.gtk.vfs.*
    [3] stable
        ID                                    Arch   Branch Remote  Download
        ID                                    Arch   Branch Remote  Download
 1. [✓] org.gnome.Platform                    x86_64 3.32   flathub 360.0 MB / 374.0 MB
 2. [✓] org.gnome.Platform.Locale             x86_64 3.32   flathub  17.4 kB / 320.0 MB
 3. [✓] org.freedesktop.Platform.VAAPI.Intel  x86_64 18.08  flathub   1.8 MB / 1.8 MB
 4. [✓] org.freedesktop.Platform.html5-codecs x86_64 18.08  flathub   3.2 MB / 3.3 MB
 5. [✓] org.gimp.GIMP                         x86_64 stable flathub 106.5 MB / 108.9 MB

Installation complete.
[mythcat@desk ~]$ flatpak update

Note that the directories 

'/var/lib/flatpak/exports/share'
'/home/mythcat/.local/share/flatpak/exports/share'

are not in the search path set by the XDG_DATA_DIRS environment variable, so
applications installed by Flatpak may not appear on your desktop until the session is restarted.

Looking for updates…
Nothing to do.
[mythcat@desk ~]$ flatpak run org.gimp.GIMP//stable

Note that the directories 

'/var/lib/flatpak/exports/share'
'/home/mythcat/.local/share/flatpak/exports/share'

are not in the search path set by the XDG_DATA_DIRS environment variable, so
applications installed by Flatpak may not appear on your desktop until the session is restarted.

GIMP-Error: Skipping '/home/mythcat/.var/app/org.gimp.GIMP/config/GIMP/2.10/pluginrc
wrong GIMP protocol version.
...

G'MIC plug-in for GIMP.

GIMP is an acronym for GNU Image Manipulation Program and it has many capabilities.
One best feature is the plugins system. Plugins may be stored in different locations depending upon your distribution.
The author of G'MIC plug-in tell us: The G'MIC plug-in for GIMP proposes a set of various filters to apply on your images, including artistic effects, image denoising, and enhancement algorithms, 3D renderers, etc.. It is a quite large plug-in, integrating a lot of different effects.
You can download the G'MIC plug-in from here.
Unzip the file and go to the folder where is the gmic_gimp file.
Use this command to copy the file in the plug-ins folder.

$ cp  gmic_gimp ~/.gimp-2.6/plug-ins/

Once you have installed the plugin just restart the GIMP.
The G'MIC will work just if you have opened an image.
You can find it on menu: Filters-> G'MIC... Also, the G'MIC plug-in has available 284 filters.