Import the files

Just open blender and put the prefer models into your scene by clicking File -Append - and then go to your downloaded folder.

For better organization the models are put in two different collections. Collection Lava Stones | Mid Poly has the high detailed models in it and the collection Lava Stones | Low Poly has the small detailed models.

Work along with the shader

To affect the amount and the pattern of magma texture, you have to change these nodes:

Select the Magma Material:

Increase the strength:

More Glow:

Less Magma:

Change the Edges of Magma: