Hello Willam,
Yes, from a technical point of view, it is possible but the best solution is to modify the texture itself.
Generally, we use the shader to have dynamic effect in Experience.
Shader is a program sent to graphic card (GPU) calculate in real time and at each frame.
So for a performance reason, it is better to modify the texture in an image editor like photoshop or the gimp.
If a shader is needed, for example, in GLSL programming shader language (used in Vuforia Studio), we can add a light to modify texture rendering.
An example here :
https://stackoverflow.com/questions/63892847/how-do-i-adjust-the-my-glsl-code-to-add-additional-light-sources
Best regards,
Samuel