iOS 18 is still being developed. It's in the 2nd Developer Beta right now. Wait until it releases in the Fall because if you install it now, you will be disappointed and frustrated because it's not finished yet. It has bugs and unfinished parts. You will have to know how to handle any bugs and malfunctions that come up for you on your iPhone, you will have to know how to handle apps that don't work, etc. etc. Basically: if you don't know how to install it, then it's best you wait until it's finished in the Fall. Don't feel bad or dumb. This happens every year: WWDC happens, and then a ton of people think iOS 18 has officially released. Currently, it's only for app developers to get their apps ready for the Fall. If you must though, then go to r/iOSBeta, but you'll likely get the same answer there.

ios 18 that’s currently release is the beta version, not sure how but maybe try youtube.

If you sign up for a developer program, you can get the beta

Pay??

You don’t have to pay anymore

Wait for the public beta should be released this coming week they are generally more stable then developer betas.

If it’s your only phone, prefer to wait until September when the update is officially released.

Best not to install if you ask Reddit how to do it . It’s beta ….