Connect your iPhone to your Mac with a USB cable
Unlock your iPhone and tap Trust This Computer if prompted
Open the Photos app on your Mac
Select your iPhone under Devices in the Photos sidebar
Choose the photos you want to import
Click Import Selected or Import All New Photos
Wait for the transfer to finish
Eject your iPhone safely from Finder or Photos when done
To sync automatically, turn on iCloud Photos on both iPhone and Mac
On iPhone, go to Settings > [your name] > iCloud > Photos and enable Sync this iPhone
On Mac, open Photos > Settings > iCloud and enable iCloud Photos
Make sure both devices are signed in with the same Apple ID
Keep both devices connected to Wi-Fi and power for iCloud syncing