Instagram allows you to retrieve the URL of public-facing posts so that you may share your photos on other platforms. Note that this method is limited to public-facing posts - posts that are classified as "private" may not be shared.
How To Get an Instagram Photo URL
Open Instagram and browse for the photo of your choice. Once found, tap on the menu button located under the photo (3 vertical dots). Tap Copy Share URL:
A confirmation message will be displayed confirming that a sharable URL has been copied to your clipboard.