I don't think so.

The size of something does affect how much magentic force it can exert.

I know someone who accidentally underwent MRI with their phone still in their pocket. It didn't go flying across the room or anything, despite containing permanent magnets.

The phone was VERY dead after, but no injury occurred.

It does depend on the machine, I think. More sensitive and powerful MRI machines can have orders of magnitude more powerful fields.