Much like the R3X, the R1X’s name suggests that it will be a high-performance version of the existing R1T or R1S.
Rivian Trademarks’ R1X Name, Likely To Be A Sportier Version

While Rivian is busy introducing its lineup for the second half of the decade, a trademark for the name “R1X” filed in 2021 has been making rounds on the internet. While there is no information or announcements regarding the R1X, it is likely to be a performance version of the current R1 lineup since Rivian uses the name R3X for a sportier version of the R3.

Some leaks and insider information suggest that the Rivian R1X might have 1,200 hp. As for its engine, it only makes sense for the R1X to come with a quad-motor setup with the huge battery “Max Pack”. Expected to go directly against the Tesla Cybertruck and GMC Hummer EV, the R1X might replace Bosch motors for its Enduro drive units for the quad-motor setup.

Another interesting thing to note is that Rivian has also filled for trademarking the names R3S, R4S, R5S, R4T, R5T, etc which makes it clear that this is just the automaker protecting its naming convention. However, the R1X is still on the cards and may arrive by the end of the decade.