I am On L1b Valid till march 2023 this year h1 got picked if i got approved through COS it will be effect from oct 2022 but if i want to continue until jan 2023 on L1 then use the new H1B will that possible ?

If you file a COS, your status changes once your H-1 gets approved or upon the Start date of the petition. Which ever is later. If you start date was written as November in your H-1 then you can start on that date. Otherwise you will have to start on October 1 or the date the H-1 gets approved, whichever is later.