There is the heckelphone, the bass oboe, the cor anglais, the oboe d'amore, the regular oboe, and the piccolo oboe. Maybe there are others.

The English horn, Oboe d' amore ,Piccolo oboe ,Oboe da caccia ,Hecklphone, Contrabass oboe.

Either soprano Oboe soprillo sax or sopranino sax or piccolo

The oboe is larger than the piccolo. The largest woodwind instrument is the contrabass saxophone.

The piccolo oboe is the smallest you can buy, but you could make yourself a mini oboe! :)