Is It Possible to Reduce Nostril Flare with Internal Excisions?

Based on your photographs, it appears you have a widened base of the nose and wide cartilage.  You would benefit from bringing in the base of the nose with wedge excisions.  This does require incisions on the outside of the nose.  However, with proper technique & placement along with meticulous closure, your scars should be nearly invisible.  You would also benefit from refinement of your nasal tip and increasing the tip projection (which would also bring in the base).

Flaring nostril can be successfully reduced by using techniques to hide scars internally at the base of  the nostril.

The base width of the tip can be wide because of horizontally oriented nostrils and/or thickened nostril rim. Your posted photos show the Afro-American or Asian type of nose with a wide base at the bottom, a round tip and a flattened bridge. Your nostril rim does not look thick. In my experience the best way to narrow the bottom of the base is to cut out a wedge from the outer corner of the nostril. That does not work if the incision is only inside the nose. To make the incision scar less visible a small flap of skin is left on the upper inner aspect of the wedge, the closure line of the wedge has to lied directly in the crease and the lower outer aspect of the wedge should stay within the shadow cast from direct overhead lighting. If you extend the lower outer edge of the wedge further it can be too visible.

I hope you realize that this format of posting questions and receiving answers lacks the face to face direct communication required for you to make an informed decision regarding your surgery.

My response to your question/post does not represent formal medical advice or constitute a doctor patient relationship. You need to consult with i.e. personally see a board certified plastic surgeon in order to receive a formal evaluation and develop a doctor patient relationship.

The incisions on the inside reduces nostril flare and the scars heal well. I do not make them on the outside since these often heal poorly.

The incisions for the alarplasty are at the base of the nostril sill, but are not completely inside the nose.  They are a simple excision of skin including a portion of the nostril base and sill that is closed with fine meticulous sutures.  This is also known as a weir alarplasty.