Is there a way to highlight words without creating a note for every single one?
Like highlighting all occurrences of 'love' in a chapter but either don't create any notes or just create one note for the whole chapter.
Unfortunately, this is the equivalent of asking is there a way to highlight words without saving a link to/the location of what is highlighted? No, it is not possible.
You could use Visual Filters as per https://support.logos.com/hc/en-us/articles/360016747431-Create-a-Visual-Filter