How do I sync my iPhone, iPad, and Mac?

iCloud is used to sync between Apple devices logged in with the SAME Apple ID/Account. You can share photos, contacts, passwords via iCloud syncing.

On a Mac running macOS 15.3.1 open System Settings->Apple Account (your name)->iCloud->Saved to iCloud->See All and select the dats you want uploaded to iCloud. Do the same on your iPhone and iPad.

Each user gets 5GB of complimentary iCloud storage. If you need more you can purchase iCloud+. Various tiers are available for a varying monthly fee.

Sign in and use iCloud.com - Apple Support

Set up iCloud on all your devices - Apple Support

Confusedto wrote:

how do I sync my iPhone to my iPad to my Mac.

The easiest way: Log each device into the same Apple Account ID, then, on each device, tap Settings, then the iCloud name at the top. Then tap iCloud and turn on the switches for the content you want to sync.

This will sync everything except Contacts, Calendar, Notes and Reminders. To sync those just log in to the same email account (or accounts) on each device.

All content with then sync, and stay in sync. It’s best to leave the devices powered, connected to power and connected to Wi-Fi to speed up the initial sync process.