Download Image from SharePoint Image column
This column formatting sample demonstrates displaying a button to download the image of the image from the Image column by Ganesh Sanap
To alter how fields are displayed in SharePoint lists and libraries, utilize column formatting. To accomplish this, you create a JSON object that specifies the items that will be shown when a field is included in a list view, as well as the styling that will be used on those elements. The column formatting solely affects how the data is presented to users who browse the list; it has no effect on the data itself in the list item or file.
https://learn.microsoft.com/en-us/sharepoint/dev/declarative-customization/column-formatting