There are two 5Gs. There is Sub-6GHz-5G and Milimetrewave 5G.

Sub-6GHz-5G operates in roughly the same frequency ranges as 4G. Radiation-wise it is pretty much exactly the same as 4G. The cell size is similar, the frequences are similar, range and object penetration are similar. What is different is that 4G was built upon 3G which was built upon 2G, which means, that 4G has very complicated and inefficient signaling and overhead compared to 5G, where they decided to declutter the protocol and make the management much easier. The main benefits of Sub-6GHz-5G are for the network operator, since it makes management so much easier. The only really meaningful advantage for the users is, that 5G allows to allocate a higher bandwidth to a single user in case no other users in the cell need it right now. This is only very rarely the case, so in most cells this won't happen often.

mmWave-5G is a different beast. It operates on frequequencies between 24-100Ghz, which is more than the max 6GHz that the otherr kind of 5G runs on. These higher frequencies are quite different. First, hardly anything else uses it, so the frequency bands are mostly empty, so you can reach incredible speeds on these bands. The problem is, there is a reason why hardly anything uses it. The range is super low (about the same range as a good wifi access point) and the object penetration is abysmal. A sheet of paper can block the 5G signal. Or a tree. Or your hand. Or your head.

So if you hold your phone the wrong way, or turn the wrong way, or have hair that covers your phone, you might not get reception at all.

So the use cases for mmWave-5G in the real world are incredibly limited, and they are usually used in a few hotspots in a larger city, just so the network providers can advertise their services as "Up to (huge number) GBit/second".

So now for the radiation argument: Both kinds of 5G are solidly inside the non-ionizing-radiation-territory, so the only thing you can do is heat something up. And heat is something you feel, so if it doesn't burn you it doesn't harm you. Other than e.g. UV radiation, which is ionizing and causes skin cancer, and yet people willingly expose themselves to UV in intensities that are 10 000x or more than what they expose themselves to 5G. They even expose themselves on purpose to UV to the point that radiation sickness (=sunburn) sets in, but the same people are afraid of 5G. Go figure.

But to really disspell the fear of 5G: Sub-6-5G is radiation-wise identical to 3G, 4G and WiFi. mmWave-5G is so weak in object penetration that it gets blocked by a piece of paper or the outer layer of the skin. And the radiation exposure is incredibly tiny.