>>12937169On land or is in water ok? Fully in water, there's probably no gravity issues but there may be biological limits on how large a creature can be and still have unified control.
If ideal conditions don't involve changing gravity, I suspect the largest land dinosaurs got to about 90% of the largest size possible but that's a wild guess on my part. In the oceans, much larger than anything we know about is probably possible but idea conditions haven't been reached in that environment.