Right way to theme in Material UI components

From the Material UI website, there seem to be multiple ways of theming, and I'm not sure which to use.

1. There's this method, which just seems to use pure React context. However, I don't see how main relates to the color. I'm not sure how it is a field that Checkbox is able to extract from, given we don't specify it in the HTML.

import * as React from 'react';
import { createTheme, ThemeProvider } from '@mui/material/styles';
import Checkbox from '@mui/material/Checkbox';
import { green, orange } from '@mui/material/colors';

const outerTheme = createTheme({
  palette: {
    primary: {
      main: orange[500],
    },
  },
});

const innerTheme = createTheme({
  palette: {
    primary: {
      main: green[500],
    },
  },
});

export default function ThemeNesting() {
  return (
    <ThemeProvider theme={outerTheme}>
      <Checkbox defaultChecked />
      <ThemeProvider theme={innerTheme}>
        <Checkbox defaultChecked />
      </ThemeProvider>
    </ThemeProvider>
  );
}

2. There's this method, which seems to make more sense. Here we explicitly extract the theme color via theme.status.danger and place it into the color field.

import * as React from 'react';
import Checkbox from '@mui/material/Checkbox';
import { createTheme, ThemeProvider, styled } from '@mui/material/styles';
import { orange } from '@mui/material/colors';

declare module '@mui/material/styles' {
  interface Theme {
    status: {
      danger: string;
    };
  }
  // allow configuration using `createTheme`
  interface ThemeOptions {
    status?: {
      danger?: string;
    };
  }
}

const CustomCheckbox = styled(Checkbox)(({ theme }) => ({
  color: theme.status.danger,
  '&.Mui-checked': {
    color: theme.status.danger,
  },
}));

const theme = createTheme({
  status: {
    danger: orange[500],
  },
});

export default function CustomStyles() {
  return (
    <ThemeProvider theme={theme}>
      <CustomCheckbox defaultChecked />
    </ThemeProvider>
  );
}

3. I could also change the MUI nested component:

import * as React from 'react';
import { ThemeProvider, createTheme } from '@mui/material/styles';
import Button from '@mui/material/Button';

const theme = createTheme({
  components: {
    MuiButton: {
      styleOverrides: {
        root: {
          fontSize: '1rem',
        },
      },
    },
  },
});

export default function GlobalThemeOverride() {
  return (
    <ThemeProvider theme={theme}>
      <Button>font-size: 1rem</Button>
    </ThemeProvider>
  );
}

Which is the right way to theme?