Notifications from your various apps vary greatly in importance and frequency, and this is something Apple has taken note of and tried to address with a variety of management options. While in the early years you could simply turn notifications on or off, you can now manage notifications by individual app. You can turn notifications off for a particular app altogether, or you can turn off the sounds or badges and decide whether you want them to show up on the Lock Screen or Notification Center or as a banners. iOS 15 introduces a new management tool - the Notification Summary.
If you are into keeping track of your daily step count and you use your iPhone's Health app to monitor it, then you probably get a little annoyed when you walk a decent distance without your iPhone. Thankfully you can manually enter data into the Health app, so if you missed out on some steps you can just enter them yourself. Obviously you'll need to know the amount of steps you missed recording, or at least have a rough estimate. You could take the walk again with your iPhone to count the actual steps or just enter your best guess.
There have been Accessibility options to change the appearance of your iPhone apps for some time now. For instance you can change the font size, use bold text, change contrast and so on. Any changes you make, however, are system wide and will affect all of your apps. Not so in iOS 15 - now you can change the appearance of apps on a per-app basis. Here's how to do it on iPhone:
Just about every iOS update improves the Notes app with additions such as note sharing, password protection, tables, folders and more, making it a much more useful app. iOS 15 continues the evolution with the addition of Tags (think hashtags), which makes it a lot easier to find the note you're looking for. Now you can categorize your notes simply by adding a hashtag (or multiple hashtags) to them, then you can search by hashtag. Here's how to use hashtags in the Notes app on iPhone:
Ambient noise, white noise, dark noise; whatever you want to call it, the App Store abounds with apps dedicated to playing background noise to help you focus, find calm, fall asleep, tap into your subconscious and so on. Apple has taken note of the general enthusiasm regarding such apps and has added its own background noise feature in iOS 15 - Background Sounds. It isn't a stand alone app, rather it is an Accessibility feature that you can use to drown out distracting noise in your environment, help you meditate, help you sleep and so on.