How would you handle this scenario? Do I design to 2018? 2024? How can I follow local amendments if they are not done yet?
As a designer IMO you should be keeping up with all future codes changes that the model codes are debating now, not just what is in the currently adopted code in the jurisdiction for your project. Lets face it, building codes and changes to them are more glacier like than a dragstrip in their changes.
As thus, keeping a project inline with the most restrictive by doing the research of what's ahead is valuable to your clients in preventing change orders later. As to a less restrictive change, revisit it as you get closer to permitting then, and only then, make a change if the plans warrant the less restrictive requirement with it being in the latest adoption by the AHJ. The bottom line is the adopted code being enforced is a minimum.
Compare the currently adopted 2018 with modifications, with the model 2021 & 2024 editions for the changes. As noted above, design for the most restrictive with a list of optional changes that might be able to be made depending on the future adoption just prior to permit submittal.
There are designers, and I believe by your post that you are trying not be one of them, that will design for the lesser restriction and push hard to submit it in before the buzzer of the new adoption. I understand the dollars and cents part sometimes, but knowingly designing something to a lesser requirement you know is coming for a published reason, depending on the reason can be sticky later on.
In my little world, which is misc. metals fabrication, we stay abreast of currently enforced through all later model codes, plus what is being debated in the most current cycles of not only the ICC and the NFPA, but any other codes and standards and other conflicts that might affect what we work on. It is part of the job and what the clients I work with expect to be delivered.