When I replaced my 5 year old phone the only two benefits I saw was OLED screen (never going without again) and the battery life going from maybe a day to like 40 hours
I just replaced my iPhone older than six years old with a 16 Pro Max… OLED to OLED, but now 120hz. Magnificent. And yeah, the battery lasts forever now.
Maybe your old phone's screen sucked. I switched from flagship 2021 OLED phone to mid-tier IPS 2020 phone. I prefer IPS, because it crisper and have more neutral colors. And more important, it doesn't have stupid waterfall edges.
My old phone screen was fine, I just hate bright lights and OLED gets way darker.
My new phone doesn't have waterfall edges, presuming that's a curved edge thing. Flat display on all sides, no side bullshit.
Another benefit of OLED, at least in my case (nothing phone 2a) is there's no polarisation layer so I can wear my sunnies and look at my phone on any angle I please, instead of rotating it making the screen vanish. Laptop still does that and it's super annoying, if I'm outside watching videos on it I just can't use sunglasses.