All districts
Canton Township allows accessory apartments, but only in the three rural districts and only as a special land use. In RA, RE, and RR, an accessory apartment needs Township Board special land use approval, a lot of at least 2 acres, a floor area of no more than 600 square feet, a design that preserves the single-family appearance, and one added parking space (Section 9.02.B.1; Section 10.02.B.1). The definition limits occupants to relatives of the principal resident, domestic servants, or gratuitous guests (Section 1.03). A detached guesthouse for temporary, non-rental sleeping use is a separate special land use in the same three districts (Section 9.02.B.2; Section 1.03).
In R-1 through R-5, R-6, MR, and RMH, accessory apartments appear nowhere in the use lists (Section 11.02; Section 12.02; Section 13.02), and the general provisions close the side doors: accessory structures may not be used as dwellings or businesses (Section 2.03.D.4), only one principal building is allowed per single-family lot (Section 2.09.A.2), and a basement without a house above it is not a lawful dwelling (Section 2.04).
So an in-law suite inside the house that never becomes a separate dwelling unit is a design question worth confirming with the Building Official, while a true second unit on a subdivision lot has no path short of rezoning or an ordinance amendment. Michigan law also protects certain licensed residential facilities regardless of local zoning. Confirm plans with Planning Services at 734-394-5170.