Fold expressions must be enclosed in (...): return ((ts == value) || ... || (false));.
Also you can drop || false, it's implicit for || folds.
Also I would like to get rid of specifying the type if possible (e.g. the
<int>)
You can do this by replacing <typename T, T ...ts> with e.g. <auto ...ts, typename T>.
But if I was you, I'd pass all alternatives as function parameters (to allow them to be changed at runtime).