If you are asking regarding places to visit here are some beautiful spots to visit. You could start with north Sikkim, move to Lachen peep into Gurudongmar lake, stop by singhik then drive to lachung view zero point, then move to Gangtok making your return easy, for Gangtok is well connected to many parts of India.
There are online Sikkim packages available on platforms like Tripoto, Agoda.com, Yatra.com, MakeMyTrip, Travel Triangle among others. Happy journey 🙌