I accidentally deleted my photo and didn’t back up on iCloud . How can I get those photos back ?

Your only hope would be if you created a backup of the iPhone while the photos were present.

Restore your iPhone, iPad, or iPod touch from a backup - Apple Support

If you did not create a backup, the photos are gone.

It depends completely on where the photo was housed.

For example, if the photo was in Camera Roll, it is now in your "Recently Deleted" photo album.

Good luck. Enjoy your Apple gear.