Sigma is spending an awful lot of time putting out lens designs for prime mirrorless lenses with f/2 maximum apertures. These are smaller and less-complicated lenses than the typically f/1.4 Art series. The designs range from a 50mm to a 68mm lens, all configured for a full frame image circle.
One of the lenses in the patent appears to be the already-released Sigma 65mm f/2 DG DN Contemporary, with the lens design shown on Sigma’s marketing page appearing to be identical to the one illustrated in the patent application filing.
The lenses all have 11 or 12 elements in almost identical group placements. There are four new designs included in the patent application.
Sigma has been designing sub-Art-series lenses for its L mount as well as Sony E mount. The series, given the letter I to distinguish it from the Art (A) and Sports (S) lines, is a bit confusing, as the 65mm lens already released also uses the Contemporary (C) series name in its title. Those recently-released I lenses have been well-regarded despite having relatively slow maximum apertures of f/2.8 or smaller.