The best way to deal with this would be to use Columns for the image and text, putting the image in one column and the text in the other, rather than having both in one paragraph. This will ensure that the text wraps below the image on mobile devices.

You can read more about columns here - https://www.joomlacontenteditor.net/support/documentation/columns/creating-and-editing-columns

A simple example for your layout could be something like this:

1. Create a new paragraph after the block of text before the image, them select the image, then use CTRL + X and CTRL + V to paste it into the new paragraph.
2. Click somewhere in this paragraph (not on the image) and click the Align Center button.
3. Click in the paragraph below the image, then drag select this paragraph and the image.
4. Click the Create Columns button, change the Stack Width to Small, and click Insert.

would columns be responsive?

Yes they are.

Which template are you using?

Yes, Columns will work fine with this. Although it does not appear to use a CSS Framework like Bootstrap or UIKit, so it will use the JCE generic columns css for columns display.