How to upload photos off my iPhone to iCloud

Set up photo library from iPhone , the photos will sync to iCloud Set up and use iCloud Photos - Apple Support

On your iPhone, iPad, or iPod touch

1. Go to Settings > [your name].
2. Tap iCloud.
3. Tap Photos, then tap the switch next to Sync this [device].

When you turn on iCloud Photos, your photos and videos automatically upload to iCloud.

Download your photos and videos from iCloud.com

1. On iCloud.com, click Photos.
2. Select the photos and videos that you want to download. 
3. Click and hold the download button  in the upper-right corner of the window. If you want to download your content as it was originally captured or imported, choose Unmodified Original. For JPEG or H.264 format — including edits, and even if it was orginally in HEIF or HEVC format — choose Most Compatible.
4. Click download.