You might find this thread helpful:
Question about how I should do stamps?
As of Nov 2022, the current postage must add up to at least $1.40 for international postage and $0.44 for domestic US postcards. Prices will be going up again in January 2023.
This is one of my favorite threads on the forum:
What stamps do you use on postcards/letters? Show us!
You can see lots of amazing examples of how people use multiple stamps to add up to the correct amount.
Easiest right now if you want to use current USPS postage is probably 2 domestic Forever stamps plus one additional ounce brush rabbit stamp, that’s 60c + 60c + 24c = $1.44 (so you’d be paying an extra $0.04 per international postcard)