To change the limit you will need to make changes in the schema of the theme. As it might be input box which you will need to change it to the text-area.
As the Booster is the paid theme so I don't have any idea about it's schema but if you can share your store access then I can assist you in achieving it.
can you past your code snippets here so I can guide you , the limit set on your liquid
find in your code truncate: 80 remove that limit