Handling json pretty print param in ASP.NET Core API application

This question is almost verbatim what is being asked on this stackoverflow question

But I'd like to do it in a ASP.NET Core Api. I'm planning on implementing it as a a header instead of in the query string. I'm struggling with changing the Json SerializerSettings that has been set in the ConfigureServices method.

services.AddMvc(config =>
        {
            config.Filters.Add(new WebApiRequireHttps());                
        })
            .AddJsonOptions(options =>
            {
                options.SerializerSettings.Formatting = Formatting.Indented;
            });

What I'm trying to accomplish is change the Serializer's settings to use Formatting.None when I've set a header like X-MyApi-Pretty: false.

I'm trying to create my own ActionFIlterAttribute like in the aforementioned question. Microsoft.AspNetCore.Mvc.Filters uses ActionExecutedContext which doesn't seem to have an obvious equivalent to ActionContext.RequestContext.Configuration.Formatters.JsonFormatter.

Is there an equivalent or am I just going about this all wrong? My google-fu is really failing me on this and I feel like I'm missing something really obvious.