Here you can find files for an alternative to the Main App icon of LibreOffice.

For MacOS, icons can use jpg or png files. I have also provided png files for this purpose. For Linux, icons can also use svg files.

If you want a different size than I have provided, and know how to open and export the svg file as a jpg/png file, well, do this first. Software is required for this; Inkscape for example.

Mac method to change desktop icon image: Open the png file with Preview and choose Edit>Copy (or cmd-c) to copy the entire image. Copy the content of the image file, not the actual file. Next, find the LibreOffice app file in Finder. Right-Click the file and choose Get Info. Select the icon image at the top right of this Info Pane; it should become highlighted when selected. Now, choose Edit>Paste (or cmd-v). That's it, done. Next time you start or restart the app, the icon will change. If the icon looks a bit pixelated (fuzzy/unclear) to you, you will have to use a larger png file or one with a higher dpi to create a cleaner look.