[material-ui][Icon] Font size is not applied to Material font icons

Duplicates

• I have searched the existing issues

Latest version

• I have tested the latest version

Current behavior 😯

Set component props as for example fontSize="small" or sx={{ fontSize: 30 }} don't modify size of icon. It doesn't work for Material Icons. Change font size for FontAwesome icons works correctly.

Expected behavior 🤔

Icon size should be changed after set fontSize="small" or sx={{ fontSize: 30 }}

Steps to reproduce 🕹

Steps:

1. Go to https://mui.com/components/icons/#font-material-icons
2. See that icon size is not changed for the two last icons

Context 🔦

I tried to insert icon and change its size using component

Your environment 🌎

  System:
    OS: Linux 5.13 Linux Mint 20.2 (Uma)
  Binaries:
    Node: 16.13.0 - /usr/bin/node
    Yarn: Not Found
    npm: 8.1.0 - /usr/bin/npm
  Browsers:
    Chrome: 95.0.4638.69
    Firefox: 94.0
  npmPackages:
    @emotion/react: ^11.5.0 => 11.6.0 
    @emotion/styled: ^11.3.0 => 11.6.0 
    @mui/core:  5.0.0-alpha.54 
    @mui/icons-material: ^5.0.4 => 5.1.0 
    @mui/lab: ^5.0.0-alpha.54 => 5.0.0-alpha.54 
    @mui/material: ^5.0.4 => 5.1.0 
    @mui/private-theming:  5.1.0 
    @mui/styled-engine:  5.1.0 
    @mui/system:  5.1.0 
    @mui/types:  7.1.0 
    @mui/utils:  5.1.0 
    @mui/x-data-grid: ^5.0.0-beta.7 => 5.0.0-beta.7 
    @types/react: ^17.0.30 => 17.0.34 
    react: 17.0.2 => 17.0.2 
    react-dom: 17.0.2 => 17.0.2 
    typescript: ^4.4.4 => 4.4.4 

Start with the examples at the font-material-icons documentation page and compare the two final Material Icons examples with the FontAwesome examples. Verify how fontSize="small" and sx={{ fontSize: 30 }} affect each rendered icon; done means both props visibly change Material font icon size as expected.