The CHELSA dataset provides access to climatologies at high resolution for the earth’s land surface areas. Among those are the global climate-related predictors at kilometer resolution for the past and future (Brun et al. 2022) - generally known as bio-climatic variables. This dataset is provided through the main CHELSA website and links to a file download option which focuses on bulk file downloads.
However, it seems that the geotiffs provided are cloud optimized geotiffs (COG files).