Often this is necessary because not all theatres have a screen of the size required to show a film in large format, or indeed the projection equipment.
In former days, it was true of the neighbourhood theatres located outside of downtown areas.
Conversely, a "blow-up print" is a regular format film converted to larger size (i.e., 35mm to 70mm).
This was once often done so that "regular-sized" film would seem even more impressive on screens such as the ones in Cinerama theatres.
Usually, the lightest colour of the design is printed first, then the block is "reduced" by carving to the areas which the artist wants to print the second colour from, and so forth.