According to information brought by WorldClim the new CMIP6 spatial data on temperature and precipitation should contain 12 layers per each downloadable file (1 layer per month) and the bio-climatic variables should have 19 layers in total.
However, when downloading the files from the page: https://www.worldclim.org/data/cmip6/cmip6_clim2.5m.html each file comes as a zip-file apparently only containing one geotiff-file. I don't know if each *.tif file could be layered, but haven't heard about it being possible? (Not like NetCDF).
I have used the WinRar for decompressing the zip-files and Surfer v. 15 for processing the *.tif files.
Thanks!