step into someone's shoes
US /stɛp ˈɪntu ˈsʌmˌwʌnz ʃuːz/
UK /stɛp ˈɪntu ˈsʌmˌwʌnz ʃuːz/

1.
to take over someone else's job or responsibility
:
•
It will be hard to step into his shoes when he retires, he's been such a great leader.
•
After the CEO resigned, the vice president had to step into his shoes immediately.
2.
to imagine oneself in someone else's situation, especially to understand their feelings or perspective
:
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If you could just step into her shoes for a moment, you'd understand why she's so upset.
•
It's easy to judge, but try to step into their shoes before you criticize.