There are a number of ways we can make heat shields.
A heat shield is using the shape of a spacecraft to keep things that need to stay cold out of sunlight – basically we’re putting them in shadow.
Some satallites already have a suitable shape built into them – e.g. if the solar panels are on the satellite instead of as wings, then we can hide things in the shadow of the solar panels. PLATO has this kind of heat shield.
For satellites that don’t have something already in their shape – we can add bits.
A really common type of heat shield is to use thermal blankets to make a big shape. Thermal blankets are made of lots of layers of aluminium foils, often we use 10 layers, but for heat shields we would use 20 or 30 layers. The advantage of using blankets is that they are flexible – so if we need a big shape, we can design something that can be folded up inside the rocket and then unfolded once the satellite is in space, a bit like an umbrella. To make sure that everything is going to unfold properly, we often make paper models of the heat shield (sometimes even origami methods) to try things out and work out the best of making something. Gaia has this kind of heat shield.
The other option for heat shields is to make an extra bit of structure – it could still use layers, but those layers would be thicker and not flexible like thermal blankets. We would then make sure that the brackets used to attatch that extra structure to the satellite don’t let too much heat conductively into the main bit of the satellite. Solar Orbiter has this kind of heat shield.
So – the simple answer is, we use “standard” satellite materials to make heat shields and they’re often constructed from layers – the big difference is that we’re using satellite materials in a different ways to how they normally are.