How do I allow css and html codes in the excerpt? I've tried editing the functions.php and installing the Advanced Excerpt plugin but nothing seems to work, it just appears blank of the front page.

For example if I wanted to use the code below to create a lable on the post only the word 'LABEL' appears. It like the code is being blocked by this theme, I've enabled other themes and it works fine.

 <p style="text-align: center;"><a href="https://www.blank.com/URL/"><GREEN>LABEL</GREEN></a></p>

When creating a new post I want to put the rough code below in the excerpt. Also shown in Screenshot 1. Then along with some CSS in creates what is shown in Screenshot 2. But in PenNews it's like the custom css and code is blocked, it only shows text, see Screenshot 3.

<p style="text-align: center;"><a href="https://www.google.com/images/"><google>Go to Google</google></a></p><p style="text-align: center;">Some text for the excerpt</p><p style="text-align: center;"><a href="https://www.google.com/"><img src="http://[DELETED].com/wp-content/uploads/2018/12/107667228_beech-tree-NEWS_trans_NvBQzQNjv4BqplGOf-dgG3z4gg9owgQTXEmhb5tXCQRHAvHRWfzHzHk-300x188.jpg" width="640" height="640" /></a></p>

Ok, thank you!