Read the environment for liquid routes
The official game page says One can dissolve into a droplet to slip through cracks and surge through tubes. Those examples suggest that narrow openings and pipe-like paths are worth examining before abandoning a route.
Avoid assumptions
Not every crack or tube necessarily creates a usable route. Let the game’s current interaction cues and controls decide the answer.
Source
Q: Can One move through any narrow space?
The official page gives cracks and tubes as examples, not a universal rule. Check each location in-game.