Don't want to come across as rude.
I would personally suggest doing some research, perhaps watching a few videos, about PC building and the components inside them. It's relatively straightforward, but if you are a complete beginner then there is a good chance during the build you may plug some cable in to the wrong port (say the power switch header in to another header) and the system won't start, or you might miss a cable that is crucial and the system won't start, there is a lot of wiring involved and it usually requires a fair bit of cable management unless you want the system to look a complete mess, which I personally cannot stand.
The build itself looks fine, pretty decent spec there, as the other poster recommended, I'd suggest going for 3600MHZ RAM.
Also, given the current GPU crisis where it's scalpers galore, I assume you have checked that that supplier actually has the 3080 in stock? Most suppliers currently are struggling with stock and there are people who pre-ordered the card months ago who still haven't received them.
I don't want to put you off building a system, I started doing it 8 years ago and I loved it, it's more enjoyable putting it together, making the small error somewhere and then troubleshooting it and learning along the way.
It's just that if you aren't aware of what each component does in the system, or how it goes together, which cables go to which ports, you could end up with a non-functioning system that will take a some troubleshooting, and for an absolute beginner that is probably not ideal.
By all means however, you're on the right site for troubleshooting, and any one of us here, including myself, would happily help you along the way.