Frizzy hair always either needs more moisture or more protein.
Silicone will just worsen the problem over time by blocking both protein and moisture from the hair. It's in almost every smoothing product, including conditioner and shampoo, and it temporarily makes hair smooth and soft, but it's just hiding and worsening the issue inside the hair.
Use a clarifying shampoo to get rid of all of the silicone build up and then test if it needs protein or not. If a wet strand is brittle and snaps easily under tension, don't add protein. You may actually have protein overload from one of your products. If it stretches and snaps back easily, it's fine. If it stretches too easily, add protein.
Or simply just add protein and see if it helps. If you add protein and it feels even drier and frizzier afterwards, then you know that whatever you have been using is too high in protein for your new grey hairs.
If you don't need protein, you probably need moisture, which means you need a silicone free treatment. Dry hair will just get drier and drier the more you coat it in silicone, which occludes moisture getting into the hair.
Most hair products don't actually help the condition of your hair, they just soak it in silicone, which temporarily makes everything look and feel ridiculously shiny and smooth, which sells products.
I used to have waist-length hair and feel down a massive rabbit hole of haircare for years. My hair was breaking from lack of hydration because I'm Scandinavian and it's so fine, so I had to cut all silicones out for my lengths to ever get hydrated and stop breaking.
Now I have a buzz cut and DGAF, but I'm happy to share my hair knowledge.