Saying to another, God won’t give you more than you can handle seeks to write off each person as an individual who must bear such hardships on their own. There is no Biblical foundation to this.
The hope of saying “It’s all in God’s plan” is to offer comfort and solace. It hints that because it’s God’s will, God will help us through it. But ‘Everything Happens for a Reason’ is not a true Christian affirmation.