If this is for DnD I think you should do it like Dragons are done. Tazelwurms should start very small, grow slowly, and never stop growing. You can still have bigger ones, and bigger ones are a bigger deal, but it doesn't preclude a small one hanging out as a familiar.
I am doing so somewhat in line with Dragons, where the size is only determinate on their age. Then in-world lore is being borrowed from the Witcher with alternate realities merging together. There will be true dragons, but there will be near-dragons as well like Drakes, and Wyverns. Wyrms would just be another category of near dragons, just predominately aquatic roles.
There are some animals that are hunched over making them look smaller irl so why not.
My thoughts exactly.
If this is for DnD I think you should do it like Dragons are done. Tazelwurms should start very small, grow slowly, and never stop growing. You can still have bigger ones, and bigger ones are a bigger deal, but it doesn't preclude a small one hanging out as a familiar.
I am doing so somewhat in line with Dragons, where the size is only determinate on their age. Then in-world lore is being borrowed from the Witcher with alternate realities merging together. There will be true dragons, but there will be near-dragons as well like Drakes, and Wyverns. Wyrms would just be another category of near dragons, just predominately aquatic roles.