Looking for help with speeding up my page (Specific issues)

Hello,

I’m experiencing some serious speed issues with my website. I have google Speedtest (Through site kit) to help me out, but there are a few things I have no clue to solve or test.

To give an overview: It’s not on the hosts end, there is enough speed and storage available, Redis, Perl, and some other things are enabled to speed up the site. I also solved most of the problems presented in Google Speed Test, but the following I can’t figure out (A-technical noob here). So I hope someone here can help me out:

Stats for computer:
Largest Contentful Paint: 1.3S (Needs improvement)
Cumulative Layout Shift: 0.397 (Poor)
Total Blocking Time: 90 ms (Good)

Ways to improve:
1. Reduce initial server response time. (Through themes, plugins, and server specifications). The server shouldn’t be a problem, the theme is The7 Theme Forest, one I’m very happy with and shouldn’t be causing problems either. I couldn’t find a plugin that could be causing problems.
2. Eliminate render-blocking resources There are a number of WordPress plugins that can help you inline critical assets or defer less important resources. Beware that optimizations provided by these plugins may break features of your theme or plugins, so you will likely need to make code changes.
(I honestly have no clue what I can do with this, I use plugins such as Smush, Async Javascript, Autoptimize, Converter for Media, Jetpack (boost), Redis, WP Super Cache, and WP Optimize to speed up the page.
3. Reduce unused CSS. Is there a way for someone that cannot code to do this?
4. Reduce unused JavaScript Is there a way for someone that cannot code to do this?
5. Serve static assets with an efficient cache policy Uhm, isn’t WP Super Cache already?

To make things even worse, these are the stats for mobile devices:
Largest Contentful Paint: 6.1s (Poor)
Cumulative Layout Shift: 0.372 (Poor)
Total Blocking Time: 2,030ms (Poor)

Ways to improve:
The same as desktops: Reduce unused Javascript and CSS, Reduce initial server response time, Eliminate render blocking resources.

Others are:
A. Serve images in next-gen formats. I think I already do that with Smush?
B. Serve static assets with an efficient cache policy. Uhm? Isn’t WP Super Cache for that?

I hope someone here can help me out because I have been battling this problem since February this year (It was an issue before, but from that time I started to notice that has a lot of effect on my site performance).

Please don’t hesitate to ask questions or give advice about plugins, I’m trying to run my website in a well-educated way, but I only know so much about website (self-taught).

Thank you for your time!

The page I need help with: [log in to see the link]