Google can spend up to 2x your daily budget as set at the campaign level but won’t exceed 30.4* that in a 30.4 day period.
Note that this 30.4 days resets whenever you change your budget.
IE:
The first of the month your daily budget is $100. They can spend up to $200 on a day but no more than $3040 in a 30.4 day period.
You change the budget to $200 a day on the 15th of the month. They can spend up to $400 on that day, but no more than $6080 by the 16th/17th of the next month (depending on how many days are in this month). But that $6080 does NOT include anything else you spent since the 1st.