Bagatelle Collection plaid blazer size ?

Bagatelle blazer Gray and tan box plaid with hint of white. Style features Notch collar Single button from closure 4 button detail on sleeve Slight padding in shoulder. Beautifully made. Plaid matches Fabric feels like faux cashmere Fully lined Wear with skirts. Jeans. Pants. Dress up or down. Great for fall. I Question the size. The only possible label indicator of size is on the care label. Please notice tag in photo. It’s marked P. I’m an 8-10. The fit is boxy and fits me perfectly. Gently worn. Excellent condition. Approx length 23.5” Approx p- p buttoned 20” Sleeve length approx 24” Please notice this is listed as s/p because size has to be listed. But check measurements since I wear a size 8-10 and am 5’8”. This fits me perfectly. Gently worn. Excellent condition.