Both Out of scope and Tax-exempt codes are normally used for non-taxable goods and services, ebarausse.
The only difference between the two is that Tax-exempt is listed in your tax reports as "no tax", while Out of scope isn't reported at all.
Although, we still recommend checking this out with your account just to make sure you're using the right code. Let me also share this support article for commonly used sales tax codes in QBO: Common Sales Tax Codes.
I'll be around if you have other questions.