Can Eurozone countries issue their own bonds? Can Eurozone countries issue their own bonds, or is this a delegated competency?

If not, how do such countries raise funds for big uncosted spending such as infrastructure projects?
Issuing bond is indeed the competence of the individual states. 

For example, you can buy 10 year bonds both from Italy and Germany, both of which are Eurozone countries:
https://www.investing.com/rates-bonds/de-10y-vs-it-10y