Global fashion brands have embraced size-inclusive advertising featuring plus-size models, yet the responses of Asian consumers to such advertising-where the average body size of women is smaller than in Western markets-have garnered little attention. This study, utilizing the S-O-R model, aimed to investigate whether the relationships among perceived actual and ideal self-congruence, perceived attractiveness and familiarity of a fashion model, and purchase intention vary based on the body size of the fashion model. We tested the hypothesized relationships using ANCOVA, confirmatory factor analysis, and multi-group structural equation modeling, analyzing 623 online survey responses from South Korean female consumers. Actual self-congruence had a greater influence on perceived familiarity in consumers exposed to a thin-sized model compared to those exposed to a plus-sized model. In contrast, ideal self-congruence had a more significant positive impact on the perceived physical attractiveness of the plus-size model than the thin-size model. Furthermore, the plus-size model's perceived physical attractiveness had a more significant positive effect on purchase intention than that of the thin-size model. This study highlights the importance of crafting advertising images that portray plus-size models as physically attractive to elicit favorable responses from Asian consumers.