Translation of "无论如何, 你一定要平安"
无论如何 means "no matter what"

The verb 要 means "need to be" here in this sentence, because it is followed by an adjective 平安(safe).

一定要平安 means " need to be  safe for sure"

If the verb 要 is followed by a noun, for example 一定要一千美元, then 要 would simply mean "need" - "need $1000 for sure"

If the verb 要 is followed by another verb, then 要 would be a modal verb in the sentence, for example: "you need to kill him"