Dependent Visa extension

Hi
I have couple of questions. Hope I should get right direction.

My and dependent Tier-2 visa expires in June 2022.(My visa start date June 2019) I have changed the job in 2020 and my new visa extends up to Sep 2023.

Q:1 When I apply to extend my dependent new Visa and how much period (another rest 2 years based on old COS or my new COS/visa validity sep 2023) ?
Q:2 Provide the dependent visa extension link.
Q:3 Can we extend Tier-2 main applicant and dependent visa for one year ?

Skilled worker extension period is subject to SW 18.1.

Dependant’s leave period is subject to SW 36.1.