How to wire a 7.4v 5200mAh battery to a servo and arduino at the same time

I am brand new at this type of stuff. I am trying to design and build a dropper device for my large agriculture drone. I will be using a 35kg servo, an arduino uno r3, a 5200mAh 7.4 battery, buck converter (if needed) and a digital LDR. I honestly need step by step instructions on how to wire stuff, or the exact stuff I need to buy to get this to work. I feel like a child but no one I have asked has been helpful and I literally need someone to hold my hand to get this to work because I have no idea what I am doing.

The headlights on the drone turn on, this makes the servo rotate and pull a pin dropping its load. I can't tap directly into the drone because the signal wire is 0.7v and I don't want to void the warranty by clipping wires.

Welcome! I would not recommend this as a first project, it is not that simple and somebody could get hurt if a mistook is made. Part list with links would be a good start and a block diagram of what you are trying to do. What is a large agriculture drone? How much current does the servo require, about 2.3A would be my guess. What is the minimum output voltage of your battery pack?

I don't understand this at all.
How does turning on the headlights make the servo rotate?

That is what I want to happen and trying to figure out. I was trying to use the signal wire to the lights to tell the arduino to rotate the servo but the signal wire is only using 0.7v which I believe is to low.

the drone itself doesn't really matter, as this will just be a plug and play solution for any drone large enough to hold it. And I know this doesn't sound like the best first project but I am not trying to get into it as a hobby and this does not exist for what I am trying to do.
Servo: https://www.amazon.com/dp/B07S9XZYN2?ref=ppx_yo2ov_dt_b_product_details&th=1
Lipo Battery: https://www.amazon.com/dp/B076Z778MJ?psc=1&ref=ppx_yo2ov_dt_b_product_detail
Arduino: https://www.amazon.com/dp/B008GRTSV6?psc=1&ref=ppx_yo2ov_dt_b_product_detail
LDR: https://www.amazon.com/dp/B0BXKJPV67?psc=1&ref=ppx_yo2ov_dt_b_product_detail

Buck Converter: https://www.amazon.com/dp/B0BXKJPV67?psc=1&ref=ppx_yo2ov_dt_b_product_detail