How can I set the height of the classic editor per post-type?

One way is to adjust the TinyMCE settings:

add_filter( 'tiny_mce_before_init', function( $settings ) {
    $settings['height'] = '120';
    $settings['autoresize_max_height'] = '120';
    return $settings;   
} );

and e.g. restrict further on post types and !block editor with get_current_screen().

Example:

add_filter( 'tiny_mce_before_init', function( $settings ) {

    $screen = get_current_screen();

    if ( $screen->is_block_editor() ) {
        return $settings;
    }        

    if ( ! in_array( $screen->post_type, ['tools', 'brand', 'company'], true ) ) {
        return $settings;
    }        

    $settings['height'] = '120';
    $settings['autoresize_max_height'] = '120';

    return $settings;
 } );