Wordpress doesn't give the ability to adjust HTML and scripts, by default.
However, by installing plugins, this can be achieved.
Please note, we are not affiliated with these plugins, and offer no guarantee for them. You may find other plugins better suit your personal requirements
Ability to adjust Header / Footer code
We've found the head-footer-code plugin to work well for us.
Please use plugin this to insert the Dependencies into the header.
Ability to add HTML to the body
We've found the XYZ HTML Snippet Generator Plugin plugin to work well, though there are alternatives.
Please use this to insert the HTML containers into the body.