Yes, a registry operator of an existing gTLD can request a change to its RSP supporting the gTLD. This is considered a change in Material Subcontracting Arrangements (MSA) and must follow the requirements set forth in the Registry Agreement and the MSA process.
Currently, the MSA process requires a technical panel evaluation and "Unknown RSP" simulation exercise for 2026 Round RSPs that do not support one or more gTLDs. However, please note that ICANN is in the process of reviewing its MSA process so that successfully evaluated 2026 Round RSPs will not need to undergo the technical panel evaluation or "Unknown RSP" simulation exercise requirements of the MSA change process, even though they do not currently support one or more gTLDs. ICANN org will send out a communication to inform all impacted parties once the update is made and ready to be implemented, currently anticipated in the second half of 2026.