Worrying about ram usage is not something you really want to spend too much time on. The phone will utilize the ram by putting as many apps that it thinks you will use into it so that when you open up the applications, they load near instant. This isn't like Windows where you want to have as much free as possible. There is a LOT of coding and a lot of thought put into the ram management of these devices by people a whole lot smarter than I am.
Back when I ran Android devices and rooted with ULV kernels and super lightweight roms, it was kinda cool to see how the operating systems back then dealt with ram. This was back in the Droid 1 days. I haven't, for many many years, worried about ram management - even back when I rooted my Note 3.
I've never worried about ram management on an iPhone - it's been fairly good for me even back when I had my iPhone 6+. Though, it was a HUGE difference going to the 6s+ with an extra gig of ram -- I could go from Telegram to the camera without having to reload the app.
The only thing I do now is sometimes double press the home button to wipe out apps that are misbehaving. I also hard boot the phone every few weeks (Home + Power - hold till it powers off).
