I updated a script from Daniel Bates (2007) (FX-Foundry) because I needed it, thus I'm sharing it.
It's a .scm, thus put it in your script directory.

You will find it in -> Layer/Multi-Layer Tools/Edit Multiple Layers Attributes...

This script allows you to change the mode, transparency, names and so of thousands layers at ONCE, useful for gif, or when using a LOT of layers that need to be change at once.

Layer name ( Like -> MyName #auto increment number)
Layer mode (Legacy and non legacy 2.10 layer's mode)
Layer Opacity (0 to 100)
Layer Visibility (tiny eye in front of layer)
Linked Layer (tiny chain in front of layer)
Lock alpha channel (the tiny chessboard below opacity slider)

All above up to 2 000 layers at once/one click


The update now takes in count all the layers' mode of GIMP 2.10 and not only few legacy from GIMP of 2007
Also changed the place to find it (see above) -> more where it belongs, few naming as it was misleading and add some sliders as it's easier/faster.

WARNING:
I AM NOT A PROGRAMMER / SCRIPTWRITER / PYTHON / WHATSOEVER!!!
it works with me on Linux, but on your computer it will explode then it will burn your house down and maybe be nuke your neighbors friendly town...
Do not download, if you do not want to be the only one responsible for having destroyed this planet.







Last but not least, this script won't be anymore useful in GIMP 3.0
Also if you have GIMP 2.99.2 (development version) and above, and have to use to switch between your current stable and the development version, you might not need it as well, as from (AFAIK) GIMP 2.99.2 you can select multiple layer and change the mode/lock alpha/visibility and so at once...
Having said all that, while waiting for a stable 3.0, you can enjoy on your 2.10.xx