Riot Games announced the changes that would arrive with the launch of ranked mode and how it will differ from the one we've seen in the beta. For one, the max rank will not have a confusing name.
Riot Games pulled an odd move when they initially named Valorant's max rank on the ladder, well, Valorant. This caused a lot of confusion, especially for streamers as their stream titles would sound odd with the word repeating itself. That era is behind us now and with the launch of ranked for the first time since Valorant's release, the maximum rank will now be called Radiant.
There will be eight tiers in total:
All ranks except for Radiant will have three tiers, through which the players need to progress before moving one division up.
Reaching higher ranks generally was easier with a full premade team as the participants could improve together and not risk having toxic teammates that give up after three lost rounds. However, this is also an issue for solo players who are at a disadvantage. Currently, there are no changes being implemented but the devs noted they are "looking into tactics to help address this problem, and plan to share more later this year".
There are some changes in lower ranks, or to be specific, in the placement matches. As you may know by now, if there is a high skill disparity between two players, they can't queue up with each other. Furthermore, placement matches happen before ranks are assigned so it was problematic to see whether two players can go in together.
Riot loosened this rule up a bit so there can be a higher disparity in their hidden MMR but there are still some limits. You can check out the full ranked details on the official site.