As well questions, to clarify your expectations. What exactly do you want? Do you want a plugin that would do that for you? Or you want code examples that would implement that kind of stuff into your form or would create front end form?

If you want plugin, then I’d suggest you’d go for ACF. Which allows to create forms for frontend. You can define them in backend and output via code or shortcode to frontend. But I warn you that ACF uses custom fields, which become slow as postmeta table size increases.

Just to clarify what I want is:
– there is an image in my media library (in a fixed folder) This is a weekly program.
– I want a user to replace this specific image file with an updated image file every week (a new weekly program)
– I don’t want user to access admin page/media library so I need a frontend solution.
– Form or page doesn’t matter. User can select new image file (with the same name and dimensions) and click replace/update to upload this image onto old one in WP folder.

Hope it is clear now.

Basically just do as done here:
https://codex.www.ads-software.com/Plugin_API/Action_Reference/admin_post_(action)
or following:
https://codex.www.ads-software.com/AJAX_in_Plugins

Depends on how you want it to be handled.

But still I haven’t figure out if you want someone to provide code with solution, or you need some direction where you can read to create it yourself.