I think not just domain extensions are important but also age, SEO rankings (including backlinks), and authority of the domain are extremely important to calculate how much you can sell your domain.
There are some website that you can use to estimate how much you can sell your domain from here https://www.freevaluator.com/ and here https://www.siteprice.org/
What matters the most in domains is their names. No matter what extension comes next, if you have a solid, short, meaningful name, it will be sold for hundreds of Dollars (if not thousands). Of course, if you have a short name plus .com extension, then you have a goldmine. There are some website that you can use to estimate how much you can sell your domain from here https://www.freevaluator.com/ and here https://www.siteprice.org/
I would recommend using either https://estibot.com or https://godaddy.com/domain-value-appraisal as they give far more accurate appraisals than most.
