Content Box on Main page in Wordpress

Hello, I have 40 websites that use ready-made WordPress themes, and they are, in fact, PBNs. Now, I want to create a box on the homepage of all of them where I can write a 10-line text, and I want it to be on the homepage. Since the themes are different, I'd like to know if there is a specific plugin for this purpose. A space where I can have a 10-line text on the homepage. Thank you.

the Box function of the Shortcodes Ultimate plugin seems to do what you need:
https://getshortcodes.com/docs-category/shortcodes/

Many these usually give the space to write anything that you need but if still cant work you can use the shortcode/snippet for it to view the writing in the website homepage.
or else use the custom builder for the homepage then you can easily add anything on homepage or any where.