How to add additional generic constraints to a method, rather than adding them to the type?

[YT-GameMaker]

    class EqualityOperatorsComparer<T> : IEqualityComparer<T>
        where T : IEqualityOperators<T, T, bool>
    {
        public bool Equals(T x, T y) => x == y;
        public int GetHashCode(T obj) => obj.GetHashCode();
    }

    public class Dictionary<TKey, TValue>
    {
        public Dictionary(IEqualityComparer<TKey> comparer) { }

        // How to achieve this, and differentiate it from the default constructor?
        public Dictionary() : this(new EqualityOperatorsComparer<TKey>())
            where Tkey : IEqualityOperators<TKey, TKey, bool>
        {
        }

        public void Func() where TValue : ISomeOtherInterface
        {
        }
    }

Should use extensions?

[RikkiGibson]

This is called "generic specialization", and doesn't currently exist in .NET. Extension methods can achieve something similar in some cases, but that requires having an instance receiver. Currently your best bet is probably to write a static Create method which includes all the constraints you want.