Can a romaji name be converted to kanji?

Hi. I am planning to change my name before going to Japan. I probably won't get a new passport first since I literally just renewed it. But Canada will provide a Change of Name Certificate and I will update my citizenship certificate to match the name. Would that be acceptable ID to use a Japanese name in Japan?
And since it would be in romaji, could I convert it to kanji to use on my ARC or when applying for a job in Japan?

Thank you for taking the time to answer

No and no.

The name on your residence card will be copied exactly from your passport.

You can establish an alias though. Although officially my name is only in romaji on my residence card, all my other documents have kanji. You'll need to talk to your city hall about the requirements, but usually official type mail with your name in kanji or katakana is required.