Hi I'm planning to connect lacie to mac A and mac B via thunderbolt 3 daisy chain.
It is visible on the directly connected mac but not on the other one.
Is there a way I can access it from the mac B without doing file sharing from mac A?
Use file sharing.
Having one drive mounted simultaneously to two computers [even if they would let you do that] would be a disaster just waiting to happen.
What if one machine updated a file the other had open? Which is in charge? Which decides which version of any file is the "correct" one?
Networks sharing is capable of handling those conflicts.