Depth of field as a calculated value most certainly does depend on the film format and is not unrelated to enlargement factor. The size of the actual circle of confusion may be the same on film, the the size of the acceptable circle of confusion, which is necessary to stipulate for the purpose of calculating a DOF table or scale, is usually given relative to format (making certain assumptions about the resolving power of the human eye, normal print sizes and viewing distances), though for any given purpose requiring greater or less enlargement, one might decide to use a larger or smaller value for acceptable CoC, or without going to the trouble of calculating it, you might decide to look at the DOF scale and stop down one or two stops from the recommended f:stop, if you think the recommendation doesn't give you a sharp enough image for your taste or your planned print size.