Let's say that we have a gaseous or liquidus compound (I don't know if elements or compounds make a difference, take this as a thought experiment), and we have a tungsten or steel block that's 5cm (or less, you choose) thick. Is there any physical method for that gas or liquid to pass through that thick heavy metal block (not by drilling etc.)?
Physically yes, but it would take a very long time because a gas or liquid would have to apply an immense amount of pressure to get through that thick of a metal. If we take water for example, the pressure required to force water through a 5 cm thick steel block at room temperature is approximately 5.5 gigapascals.

It's important to note that gases and liquids are not able to pass through solid materials like a steel or tung
This is for a science fiction setting, in which this gas or liquid needs to be "sealed" within a confined space for narrative reasons, but I want to understand whether this is at all possible through real-science.

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I'll assume that you mean a stationary situation, i.e., that you don't want the heavy metal block to move.

If the compound is a gas under normal conditions (temperature and pressure),