Taxonomy Generator is a free online tool to create custom taxonomy easily and quickly. You can use it without installing Meta Box core plugin.
Set up a New Custom Post Taxonomy
Set up General Options
Open this tool here and put the Plural Name, Singular Name and Slug of your custom taxonomy in the General tab. The Function name and Text domain already have default values, but you can change them as well.
Set up Labels
The Labels tab lets you enter the labels of your custom taxonomy that will show up in the Admin Dashboard.
Set up Advanced Options
In the Advanced tab, just read the description of each field. They will help you set up some advanced options for your custom taxonomy.
Remember that if you tick the box Public?, it can query to take the data of your custom taxonomy so that the content of it can be displayed on the front end.
For more detail about all the fields in this tab, please read this instruction from WordPress.
Set up Post Types Tab
The Post Types tab lists the two default post types Post and Page here. Just decide whether your custom taxonomy will display in your posts or pages.
Generate Code and Insert It to the Functions.php File
When you complete all steps above, click the Generate Code button. Just wait a moment and the code will show up right under the button.
Copy the code and insert it to the
functions.php file and it's all done.