Get type from variant at compile time

I need to do a typecheck on whether a variant type can hold a type at compile time.

I am converting an enum and a string to a variant, but I want the library to be compatible with a user provided variant (for the types they support). I would like to return nullopt if I can't create a valid variant.

template <typename CustomVariant>
std::optional<CustomVariant> AsCustomVariant(LargeEnum type, const std::string& name) {
  case LargeEnum::ALPHA:
  case LargeEnum::BETA:
    return ConvertAlphaBeta(name);

  case LargeEnum::GAMMA:
    return ConvertGamma(name);

  case LargeEnum::DELTA:
    return ConvertDelta(name);

  case LargeEnum::EPSILON:
    return ConvertEpsilon(name);

  default:
    return std::nullopt;
}

The idea is to use some sort of template magic that can do something like:

if (std::type_can_convert<CustomVariant, Gamma>) {
  return ConvertGamma(name);
} else {
  return std::nullopt;
}