This is the primary time people say "Daudz laimes, Latvija!" to celebrate the Proclamation of the Republic of Latvia in 1918.
If you want to use the "Daudz laimes" (much happiness) format for other occasions, you can adapt it:
"" (literally "Much happiness, Latvia!") is the standard phrase used to wish the country a happy birthday or independence day. While commonly heard during national holidays, it is part of a broader set of celebratory greetings in Latvian culture. When to Use It