std::chrono::year_month_weekday::operatorsys_days,(3)

NAME
std::chrono::year_month_weekday::operatorsys_days, - std::chrono::year_month_weekday::operatorsys_days,

Synopsis
   constexpr operator std::chrono::sys_days() const noexcept; (1) (since C++20)
   constexpr explicit operator std::chrono::local_days() const (2) (since C++20)
   noexcept;
   Converts *this to a std::chrono::time_point representing the same date as this
   year_month_weekday.
   1) If year().ok() && month().ok() && weekday().ok():
     * If index() == 0, returns a sys_days that represents the date 7 days prior to the
       first weekday() of the year and month.
     * Else, returns a sys_days that represents the date (index() - 1) * 7 days after
       the first weekday() of the year and month.
   Otherwise, the returned value is unspecified.
   2) Same as (1), but returns local_days instead of sys_days. Equivalent to
   local_days(sys_days(*this).time_since_epoch()).

Example
// Run this code
 #include <chrono>
 #include <iostream>
 using namespace std::chrono;
 int main()
 {
     constexpr auto ymwd{Tuesday[2]/11/2021};
     std::cout << ymwd << '\n';
     // convert from field-based to serial-based to add hours
     constexpr auto sd = sys_days{ymwd} + 24h;
     std::cout << sd << '\n';
     constexpr auto ymd = floor<days>(sd);
     static_assert(ymd == November/10/2021);
 }

Output:
 2021/Nov/Tue[2]
 2021-11-10 00:00:00