What you're seeing is almost certainly a domain swap or authority transfer technique combined with cloaking — not a 6 day domain genuinely ranking on its own.
Here's what's actually happening underneath:
The domain showing in search is new, but the authority behind it isn't. The operator has either 301 redirected from an aged domain with existing rankings, or transferred the authority from a previously ranked property onto the new domain.
A 301 redirect passes authority faster than most people realize — especially if the aged domain has years of crawl history and clean backlink profile. Google picks up the new domain quickly because it's reading the redirect as a permanent move from a trusted entity it already knows.
The cloaking part is separate from the authority play. They show Google a clean version of the site during crawling, while actual visitors see casino content.
This lets the domain pass initial quality checks and get indexed fast.
The combination — aged domain authority via 301 redirect, plus cloaking for the actual content — is a well-known setup in competitive iGaming markets, especially in SEA where operators rotate domains frequently to stay ahead of manual actions.
The 6 day domain itself isn't ranking.
It's inheriting authority from something much older underneath. The age shown in WHOIS is just the registration date of the new domain — not the age of the authority powering it.