I think you can write something like a cover letter:

Dear Sir/Madam,

I would like to submit my manuscript titled '…' to your journal.

The study addresses ….

It indicates that ….

I hope the manuscript will turn out to be valuable as so far not many studies presenting … have been published.

Yours Faithfully,

Your name

I think you can write something like a cover letter:

Dear Sir/Madam,

I would like to submit my manuscript titled '…' to your journal.

The study addresses ….

It indicates that ….

I hope the manuscript will turn out to be valuable as so far not many studies presenting … have been published.

Yours Faithfully,

Your name

Besides, you may also give this comment:

I would prefer to choose the free online color version that will only appear in color on the journal site and not in the printed version of the journal, if accepted for publishing. Or vice versa.

I prefer to write a cover letter ...

I think the content of the cover letter is good to put inside de box.

Cover letter is the best choice of this box. you can find a format of the cover letter in this links:

https://wordvice.com/journal-submission-cover-letter/

I think similar to cover letter but explained the importance of topic as well as the journal credibility