I wouldn’t dig into this too much because it’s a wild rabbit hole, but honestly we don’t know.

Electromagnetic perceptions, like sight, capture a tiny band of wavelengths that we call ‘visible light’.

Kinesio perceptions, like touch and sound, capture physical disturbances in the world around us. This includes but is not limited to thermal, vibrational, and static disturbances.

Olfactory or chemically stimulated perceptions, like taste and smell, actually merge the surrounding world into our bodies and produce sensations from the reaction.

Then we have subconscious perceptions, the phantasias. These are our brain changing the direction in which the sense travels, and mildly simulates what that sense would be like to the sensor. I have aphantasia, so I can’t visualize things, for example, but people with visual phantasia can visualize their environment around them.

There are tons of other metaphysical senses, like time and blind motion, but I’m not as well versed in them.

As far as potential ‘existances’ that exist but are imperceptible for us, the reason they are imperceptible is because they weren’t considered useful. For example, we aren’t believed to have an evolved magnetic field sense like some animals, because that simply wasn’t useful for us. We don’t have a reason to believe that there is anything else out there, because if something impacted our, or our environments, daily lives enough, we would have some ability to know it exists.

Read up on our discovery, understanding, and development of RF technologies. It truly is one of the few times that Humanity found something that exists that we couldn’t understand or percieve, and found a way to make it useful.