Try the following:
for /R "C:\root\folder" %%I in ("*.zip") do ( "%ProgramFiles(x86)%\7-Zip\7z.exe" x -y -o"%%~dpI" "%%~fI" )
or (if you want to extract the files to a folder with the name of the zip file):
for /R "C:\root\folder" %%I in ("*.zip") do ( "%ProgramFiles(x86)%\7-Zip\7z.exe" x -y -o"%%~dpnI" "%%~fI" )
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