How do i add a watermark to images on my site?

Try reviewing https://www.wpbeginner.com/plugins/how-to-automatically-add-watermark-to-images-in-wordpress/

And https://www.ads-software.com/plugins/search/watermark

@t-p @sterndata

The plugins you mentioned add a watermark when uploading images. I want to add a watermark to the images uploaded on my site. How can I do that?

I’d ask the authors of one of those plugins if there’s a bulk tool to handle already uploaded images.