Writer's Relief, is it, or other websites like it, effective at promoting authors?

I just popped over to their pricing page, which offers a lot of services and the colours are kind of making my eyes bleed so I haven't read in-depth or anything.

Social media: there are companies that do this. Most of the good ones charge a LOT because it's a valuable service, though not one most authors need. What you want to avoid with these is places that just set up all kinds of auto-posts to spam all your followers. Not cool.

You said they do web design, which is also something lots of legit companies do, usually for orgs that require fairly unique or complex websites. Wordpress is a more than capable tool for making a quick, functional author website. I know next to no CSS and only basic HTML, and I can make a good WP site with my own intuition and the tutorials provided. I'd be sceptical of offering anyone money to set up a basic website, though I know some people choose to do this for convenience reasons.

The big red flag is that they send submissions. This is, as far as I understand, a NO. What's worse, their "Elite" pricing plan sends subs every 2 months, "from their office" (does this mean the non-elite are sent through the Caymans or something? We can only hope...). It's bad form to not send submissions yourself. If you re-send the same submission to the same place every 2 months... not smart.

At best, they're a submissions tracker, which you could do easily enough yourself on an Excel spreadsheet. At worst, they're sending form letters to literary agents. Even rewritten form letters are identifiable as such at twenty paces and will not get you a positive result. You're far better off going through the process of learning to write a query yourself. You're going to need to learn it anyway and it's cheaper.