Wordpress theme options page template.

my-theme-settings.php

<?php
add_action( 'admin_menu', 'my_theme_add_admin_menu' );
add_action( 'admin_init', 'my_theme_settings_init' );


function my_theme_add_admin_menu(  ) { 

    add_menu_page( 'Theme Settings', 'My Settings', 'manage_options', 'my_theme_settings', 'my_theme_options_page', 'dashicons-admin-tools', 200 );

}


function my_theme_settings_exist(  ) { 

    if( false == get_option( 'my_theme_settings' ) ) { 

        add_option( 'my_theme_settings' );

    }

}


function my_theme_settings_init(  ) { 

    register_setting( 'pluginPage', 'my_theme_settings' );

    add_settings_section(
        'my_theme_pluginPage_section', 
        __( '1337 section description', 'my_theme' ), 
        'my_theme_settings_section_callback', 
        'pluginPage'
    );

    add_settings_field( 
        'my_theme_text_field_0', 
        __( '1337 text field description', 'my_theme' ), 
        'my_theme_text_field_0_render', 
        'pluginPage', 
        'my_theme_pluginPage_section' 
    );

    add_settings_field( 
        'my_theme_checkbox_field_1', 
        __( '1337 checkbox field description', 'my_theme' ), 
        'my_theme_checkbox_field_1_render', 
        'pluginPage', 
        'my_theme_pluginPage_section' 
    );

    add_settings_field( 
        'my_theme_radio_field_2', 
        __( '1337 radio field description', 'my_theme' ), 
        'my_theme_radio_field_2_render', 
        'pluginPage', 
        'my_theme_pluginPage_section' 
    );

    add_settings_field( 
        'my_theme_textarea_field_3', 
        __( '1337 textarea field description', 'my_theme' ), 
        'my_theme_textarea_field_3_render', 
        'pluginPage', 
        'my_theme_pluginPage_section' 
    );

    add_settings_field( 
        'my_theme_select_field_4', 
        __( '1337 select field description', 'my_theme' ), 
        'my_theme_select_field_4_render', 
        'pluginPage', 
        'my_theme_pluginPage_section' 
    );


}


function my_theme_text_field_0_render(  ) { 

    $options = get_option( 'my_theme_settings' );
    ?>
    <input type='text' name='my_theme_settings[my_theme_text_field_0]' value='<?php echo $options['my_theme_text_field_0']; ?>'>
    <?php

}


function my_theme_checkbox_field_1_render(  ) { 

    $options = get_option( 'my_theme_settings' );
    ?>
    <input type='checkbox' name='my_theme_settings[my_theme_checkbox_field_1]' <?php checked( $options['my_theme_checkbox_field_1'], 1 ); ?> value='1'>
    <?php

}


function my_theme_radio_field_2_render(  ) { 

    $options = get_option( 'my_theme_settings' );
    ?>
    <input type='radio' name='my_theme_settings[my_theme_radio_field_2]' <?php checked( $options['my_theme_radio_field_2'], 1 ); ?> value='1'>
    <?php

}


function my_theme_textarea_field_3_render(  ) { 

    $options = get_option( 'my_theme_settings' );
    ?>
    <textarea cols='40' rows='5' name='my_theme_settings[my_theme_textarea_field_3]'> 
        <?php echo $options['my_theme_textarea_field_3']; ?>
    </textarea>
    <?php

}


function my_theme_select_field_4_render(  ) { 

    $options = get_option( 'my_theme_settings' );
    ?>
    <select name='my_theme_settings[my_theme_select_field_4]'>
        <option value='1' <?php selected( $options['my_theme_select_field_4'], 1 ); ?>>Option 1</option>
        <option value='2' <?php selected( $options['my_theme_select_field_4'], 2 ); ?>>Option 2</option>
    </select>

<?php

}


function my_theme_settings_section_callback(  ) { 

    echo __( 'This section description', 'my_theme' );

}


function my_theme_options_page(  ) { 

    ?>
    <form action='options.php' method='post'>
        
        <h2>Theme Settings</h2>
        
        <?php
        settings_fields( 'pluginPage' );
        do_settings_sections( 'pluginPage' );
        submit_button();
        ?>
        
    </form>
    <?php

}

?>