No, you cannot extend your Ireland Visit Visa once you are in the country. The Visit Visa allows you to stay in Ireland for a maximum of 90 days. Please ensure you leave before your visa expires. If you want to visit Ireland again, you'll need to apply for a fresh visa from your home country or where you legally live. Staying longer than permitted or trying to extend your stay without permission can lead to fines, deportation, and make it harder for you to get visas for Ireland or other countries later on.