If the value in the input field is not valid

Hello,

I have a form field like below
A middle entry is the tax number entry
I check this tax number with live verification
Returns 1 if the tax number is valid, 0 if it is invalid.
Like “required” via browser without using Javascript/Jquery
Is it possible to show message like content is invalid?

<form>
<input type="text" required>
<input type="text" required>
<input type="text" required>
<input type="text" required>
<input type="text" required>
<input type="text" required>
</form>
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