What needs a reservation
Visits the official site says must be booked in advance. Booking goes only through each place’s own official page; nothing here points to resale or agent sites.
Kennin-ji
8 Nov
8 Nov viewing is by reservation
“Autumn Evening” special viewing, reservation only, ¥5,000.
Official site ↗圓光寺
10 Nov–10 Dec
Reservation required
Reserve a date and time (open since 20 Oct, 9:00); groups of 10+ phone first. No reservation outside the special period.
Reserve (Enkō-ji’s official booking page) ↗