There are any number of guides for the Monuments of Paris. Many are free, some charge an entry fee and a few need reservations.
https://parisjetaime.com/eng/article/parks-from-which-to-admire-the-bastille-day-fireworks-a502
Eiffel Tower. You can pay 10,20e to climb the stairs (first & second levels), 16,30e for a "Lift" (elevator) ticket to the Second Level or pay 25,50e for a ticket to visit all three Levels. E-tickets are available. A final ticket type (stairs to Second Level then lift to the top, 19,40e) is only available at the Tower. The Eiffel Tower opens at 9:00 and closes at 0:45 AM (last access is midnight). You must now go through a security check before entering the area around the Eiffel Tower. Plan in advance; lines will get very long in the summer. Definitely visit the website prior to your visit to see where the entrance/security gates are located.