If it is domain that you are going to use for something that would not be easy to change it is a good idea to not only get it for 10 years, but also every year add another year so that expiration is always 9 to 10 years out.

That way if there ever is a big price increase sufficient to make you switch domains you've got at least 9 years to execute the switch.

Unless the prices go down! You never know.

But if you see some promotional pricing on renewals or transfers, remember that you can add a few years anytime and not just on your registration anniversary. And when you transfer a domain, most of the cases it extends by a year too (although for some very rare ccTLDs that might not be the case I think).

This is especially true if you're paying with a currency that's experiencing high inflation and the price hasn't been adjusted yet. You can get a very good deal, so might as well buy all you can.

Consider using 9 years instead of 10. The reason is that if you want to transfer your domain to another registrar, it will often result in a +1 year bump because a transfer usually acts as an anticipated renew.

If your domain is already expiring in 10 years and you want to transfer out, you're stuck for a year.