To add 3 buttons under Portfolio Title, like this.
or this.
#1 . First, find Portfolio Item URL
In my example, we will have
/projects/harvard-university
/projects/stanford-university
/projects/university-of-oxford
/projects/university-of-cambridge
#2. Next, click Plus icon in Not Linked
#3 . Next, choose Blank Page
#4. Make sure Page Name/URL is
Name: Project Extend
URL Slug: /project-update-text
#5. Add some hyperlink text like this.
We will have result like this
#6. Install this plugin (free plugin)
Plugin will give you some code. You can add it to Code Injection > Footer.
#7. Use this code to Custom CSS.
div.portfolio-description a {
background-color: #000;
color: #fff;
padding:5px 10px;
display: inline-block;
margin-bottom: 10px;
}