Change materials blend mode at runtime?

A switch between blend modes would require a recompile of the shader. I doubt that is possible during runtime, but even if it was, the shader recompile would result in an undesirable slow response. As you only need two variations I would just swap the materials.

@Nicolas3D that node would only allow interpolation between parameters within a material. Blend mode can’t be set with a parameter.

I have an object that when in range of the player becomes transparent so I was wondering if you could change that materials blend mode (opaque to translucent) at run time using C++ or would it be easier to just have two separate materials and swap them at run time instead?

No need to use C++ as far as I saw, you can easily blend two materials inside Blueprints using the node “interpolate material instance” and set the range/ area trigger

Actually I’m using a Lerp node with a scalar parameter which controls the value, I’m swapping textures at runtime using the scalar parameter, and it works perfectly.
Not sure if it could work with the translucency, but yes, better create two MIC and modify what you need, then swap them.