Colour changing foundation

[readingisallowed]

Are they worth getting and if so which one.
I'm 65, have good fair skin. No deep lines.
Dry on my forehead only.

Not really. They don't colour change, they're just a low coverage foundation that contains tiny beads of pigment in a white base.

I'd go for a BB cream in your situation.

My understanding is that they don’t really adapt to your skin tone, they are just very sheer so your natural colour can be seen underneath. I think they’re a bit gimmicky. A tinted moisturiser/bb cream/cc cream would do a similar job, whereas if you wanted coverage then a normal foundation would be a better option