To see whether your battery might be due for an upgrade, open Settings > Battery > Battery Health. Head to Settings > General > iPhone Storage. Even better, use MagSafe, if your iPhone supports it, so you can hold your iPhone while its charging. In fact, it works with iPhones as old as the iPhone 11, which dropped back in 2019. While you need an iPhone 15 Pro or newer to run Apple Intelligence features, I'd wager most of us don't need these.