Can you adjust aperture on iPhone cameras?

Can you adjust how much light the iPhone camera lets in?
If not, are there other ways to do it? Like adding a special lens to your phone? I know the cinematic mode tries to do this digitally, but it doesn’t always work perfectly. Any advice would be appreciated!

While some phones once experimented with variable apertures, iPhones didn’t adopt this feature, and it’s fallen out of common use.

However, you can still aim for background blur by adjusting your subject’s size and your distance from it.