Myrrh, Frankincense, and Steel: Kurald Galain's Guide to the Magus

[Cieyrin]

is there any way to use magus as dedicated tank in caster only party

They're usually a striker class but they can also be a dodge tank if they buff for defense straight out of the box; the Armored Battlemage archetype has access to early heavy armor proficiency, though it's generally not considered a very good trade. Skirnir, which is a shieldmaiden type Magus, is probably the better choice.