How do you access parent widget elements?

Question

I'm completely new to flutter/dart and trying to understand how things work, apologies in advance for this question.

I'm trying to learn how to re-size columns and containers, and have the following container:

AdaptiveContainer(
              constraints: const AdaptiveConstraints.medium(),
              columnSpan: 12,
              padding: const EdgeInsets.all(24.0),
              color: Colors.yellow,
              child: const CenterWidget(),
            ),

I wanted to try adding a child container that scales the font size based on the constraints like so:

import 'package:flutter/material.dart';
//import 'adaptive_container.dart';

class CenterWidget extends StatelessWidget {
  const CenterWidget({Key? key}) : super(key: key);
  Widget _buildMyWidget(BuildContext context) {
    return Center(
      child: Container(
        constraints: BoxConstraints.expand(
          height:
              Theme.of(context).textTheme.headline4!.fontSize! * 1.1 + 200.0,
        ),
        padding: const EdgeInsets.all(8.0),
        color: Colors.blue[600],
        alignment: Alignment.center,
        transform: Matrix4.rotationZ(0.0),
        child: const Text(
          'Hello World', ***change text size here***
        ),
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return Builder(
      builder: _buildMyWidget,
    );
  }
}

Does this line give me access to the parent container?

Widget _buildMyWidget(BuildContext context)

My understanding is that when I call CenterWidget(), the context should have the constraints of AdaptiveContainer?, since I've defined it as medium()?

I tried a bunch of weird stuff like setting a global, trying to find out where in context.owner.buildScope() I can find it, but I think I'm lost in my understanding.

On a plus note, I've got it making the containers, and I've customized them, and figured out some basic theming, but this is stumping me. Thanks for your help and patience.

Edit: Got some help below, and this is what I have now which gives me the result I'm looking for:

class CenterWidget extends StatelessWidget {
  const CenterWidget({Key? key, String? constraints}) : super(key: key);
  Widget _buildMyWidget(BuildContext context) {
    return LayoutBuilder(builder: ((context, constraints) {
      if (constraints.maxWidth < 600) {
        return Center(
          child: Container(
            constraints: BoxConstraints.expand(
              height: Theme.of(context).textTheme.headline4!.fontSize! * 1.1 +
                  100.0,
            ),
            padding: const EdgeInsets.all(8.0),
            color: Colors.blue[600],
            alignment: Alignment.center,
            transform: Matrix4.rotationZ(0.0),
            child: Text(
              'Hello World',
              style: Theme.of(context).textTheme.headline2,
            ),
          ),
        );
      }
      return Center(
        child: Container(
          constraints: BoxConstraints.expand(
            height:
                Theme.of(context).textTheme.headline4!.fontSize! * 1.1 + 200.0,
          ),
          padding: const EdgeInsets.all(8.0),
          color: Colors.blue[600],
          alignment: Alignment.center,
          transform: Matrix4.rotationZ(0.0),
          child: Text(
            'Hello World',
            style: Theme.of(context).textTheme.headline1,
          ),
        ),
      );
    }));
  }

  @override
  Widget build(BuildContext context) {
    return Builder(
      builder: _buildMyWidget,
    );
  }
}

I just thought there was an easier way to determine if I'm using xsmall, medium, or large window.