The core muscles, are very often confused for "the abZ bruh", but in reality they include the pelvic floor muscles, the transversus abdominis, multifidus, internal and external obliques, rectus abdominis, erector spinae (sacrospinalis) especially the longissimus thoracis, and the diaphragm.

The lumbar muscles, quadratus Lumborum (deep portion), deep rotators, as well as cervical muscles, rectus capitus anterior and lateralis, longus coli may also be considered members of the core group, while minor core muscles include the latissimus dorsi, gluteus maximus, and trapezius.

So yeah, when it comes to strengthening your "core", simply doing crunches won't cut it.