One note is that if the trailer has a 7-pin plug (semi-common on Trilliums), and your car has a 4-way flat, you won't easily find an adapter to go that way (because they don't expect you to "downgrade" capability in that direction).
Both the trailers I've had did
have the 7-pin round plug, and neither had brakes
(one not installed; the other not hooked up). I already had a 4-way flat on my car. What I did was have a hitch shop make me up a 4-way car to 7-way trailer adapter. It was ready when I got there a half hour later and cost $17 Canadian.
For the long term, you might find a trailer with brakes
or might want to have brakes installed (especially towing with a fairly small car). At that point (or now), you would want to have a brake controller wired into your car, and then you would no longer have the 4-way flat on the car.
I don't really understand someone saying the 4-way flat is "appropriate for the Camry" unless your towing rating is so low that you wouldn't conceivably have a trailer with brakes (say, if your car was only rated to tow 1000# or less; but then you wouldn't be getting a Trillium
anyway). Otherwise, it makes more sense to match the car plug to what you want (4-way will give you lights
; 7-way will give you brakes and charging if you are set up for them).
If you know you don't ever want to use a trailer brake controller, then the 4-way flat will work "permanently," potentially with aforesaid adapter if the trailer has a 7-pin connector.