Under IEC62368-1, these types of symbols are called instructional safeguards. You can't (or wouldn't want to) rely upon an instructional safeguard to provide essential safety, in most cases. After all, an ordinary person may completely not see or understand the symbol(s) at all. In fact, I do not believe any standard lets you "protect" ordinary people from electric shock, by means of an instructional safeguard. For ordinary people, electric shock risk must be mitigated by "real" countermeasures, i.e. isolation, voltage limitation, and leakage current limitation.
However, some products (or situations) are inherently more dangerous than others and you cannot remove the risk completely. For example, equipment which needs to remain powered while being serviced may present some risk to the skilled person involved. In this case, an instructional safeguard may be used to warn the skilled person of potential danger.
So, practically speaking, these types of symbols probably make the most sense when directed at a skilled/trained person. For instance, they can be placed on an access panel door, or added to a PCB which carries mains or high voltage. You can put it on the enclosure of your product, but that somewhat implies that the product (as a whole) is not intended for ordinary people.
If you have access to it, I think IEC62368-1 actually does a pretty good job at covering risk mitigation. They address different types of "energy sources" and different energy levels of each type. Off the top of my head, it discusses:
ES: Electrical source (shock hazard)
TS: Thermal source
PS: Power source (actually not really sure the difference between TS and PS)
RS: Radiation source (X-rays, etc.)
MS: Mechanical source (moving parts, etc.)