Ditto command and wildcard on Catalina?

I've learnt a bit about ditto and tried this:

mkdir testingdir

ditto myfile.css testingdir

which seemed to work.

How could I ditto one file , e.g. myfile.css to several folders within testingdir, e.g. dir1, dir2, dir3 using zsh on Catalina?

Learning about ditto and tried Google'ing but am not sure.

You need to use a for loop for this (works in both zsh and bash):

for target in "dir1" "dir2" "dir3"; do
    ditto -- "myfile.css" "testingdir/$target"
done

If the target directories are actually called dir1 etc you can use wildcard expansion

for target in dir[1-3]; do
    ditto -- "myfile.css" "testingdir/$target"
done