Use what the owner's manual recommends. You live in Florida, I wouldn't go thinner unless it's spec'd.
Just as an aside, I always wondered why people would go thru the (initial and ongoing) expense of driving a so called luxury car and then ask us if it's Ok to pinch a few pennies by disregarding the manufacturers recommendations. The answer is that they know more than we do.
Toyota didn't recommend a 5W-20 for this application.
OTOH, many 5W-30s of the time would have sheared to twenty grades anyway.
If this car typically crawls through Miami Beach traffic with the AC blasting or if it's driven to NYC every other weekend four up with gobs of gear in the trunk at speeds never less than than ninety or so, a 5W-20 might not be suitable.
If the car is driven normally and doesn't see a lot of heavy traffic or hard highway runs, then a 5W-20 would probably work.
You won't know until you try it and UOA it.
You won't do any serious harm in using it.
Maybe a couple of notches more wear metals in a UOA but nothing catastrophic.