It is not the holding of the microfone in your hand that enables amplification of what you are saying, but speaking directly into it.
Sometimes we lose what speakers have to say because of inadequate microfon use. Here are a few hints to get heard properly.
Handheld Microfones
Keep in mind that microfones have characteristics, e.g., from which angles they take up signals, such as your voice. In public speaking, such as conferences, amplification via speakers is on the sides of where you speak. If the microfon picks up signals from the speaker, we will get feedback (or we use professional, expensive equipment). So the microfones in these settings typically have a limited angle to pick up signals, your voice.
In short, speak close to the microfon and into the microfon.
Keep in mind that when you turn you head, you have to move the microfone as well. Imagine a rubber band between your mouth on the microfon.
See more details e.g. How to Talk Into a Microphone or how to hold a microfon
Clip-on or Headset Microfones
are designed to pick up voice from a single position: the clip-on- below your neck, facing up- or headset along your cheek pointing forward. They work best and perhaps only from there.
Do not move them or e.g., take them in your hand to hold directly in front of your mouth, that will makes things worse. If the sound is not good, look at the transmitter, typically a box for a pocket, look if it is turned on there, maybe if there is a gain to increase, or check transmission or receiver settings. The latter are better in the hands of some sound person knowing that to do.
Be aware of clothing that my have contact with the clip-on, which may create noise when you move.
Think of a place to put them before you speak, some clothing styles do not lend themselves easily or can create awkward situations between you and a session chair meaning to clip it.