Can you only wear a foundation+concealer combo?
A primer would be optional here, not necessary.
A primer’s function is to create a smooth canvas and increase the longevity of your makeup. If you have dry skin primer can be skipped completely, however if you have oily skin then a primer might help keep your makeup on longer by preventing the oil from coming through.
Without any foundation/coverage, your skin has natural flushing and color variations based on (even minimal) sun exposure – basically, you are naturally a little bit blushed and a little bit bronzed because you are alive and have blood and go out in the sun.
It’s part of what makes you look alive and healthy.
One reason blush and bronzer can be “important” to a finished face of makeup is that when foundation covers up acne scars and minimizes pore size, it’s also covering up the color variations that might have been desirable. So we have to add the blushing and the bronzing back in to bring back the rosy cheek and the sun-kissed forehead. Without any blushing or bronzing, a flat application of one color of foundation can make a person look artificial or painted.
It’s a weird thing where adding a bit more makeup can help you look LESS like you have a ton of makeup on.
You have two choices when it comes to foundation: adding a tiny bit of that color back in after adding coverage, so you get that “alive” look back to your skin, or pick a perfect color of foundation/ concealer so you can apply it ONLY where needed, and go with minimal coverage.
I say look for a good primer, especially since some primers can have a “blurring” effect that some people find to be enough coverage to feel good about their otherwise bare skin. Even if you do decide to go in with concealer/foundation, a good primer will help you get the best effect with the least amount of foundation, and will help the foundation move across your face better.