Datepicker - I need all the dates should be selected in calendar

Date Picker - need the option to select next month date on current month calendar if it’s possible
in the account, I create the call activity in date picker I need the next month’s day to be enabled.
I found the solution where “selectothermonth : true”
but I don’t no where to add it
can anyone help me with these problem

in date picker the dates 1,2,3,4 I can’t select them any option to enable them

Please don’t create duplicate posts