Firstly, please add any code in your forum post in a code block.
Plus, note that if you have contacted Wix Support and put in a support ticket through them, then they will just refer you to this Wix Corvid Forum as they don’t deal with any code issues, which is what this forum is for.
The tutorial that Constantin linked to is correct for what you are trying to do here.
https://support.wix.com/en/article/corvid-tutorial-creating-a-show-more-link
Plus, I would suggest that you read the article carefully and fully understand the different sections for the full and short text and the show more button or the show more/show less toggle.
Also, the different code too for if you are using static text that is typed fully into the text box element on your page, or if you are using dynamic text which is coming from a dataset instead.