My kids are teens, so I'm speaking from my own experience as a 20-something.
Be a safety net if they need help. Don't bail them out of every little thing - adults need to learn how to adult - but let them know that if the $h!t really hits the fan, you have their back. Encourage them to take reasonable risks in life, but talk to them about backup plans if it doesn't work out.
Start to treat them like adults. Talk to them the way you'd talk to your own friends. Within boundaries, of course. But it's OK to talk about budgeting, work, life planning, vacations, and everything else you talk to other normal adults about. Don't keep treating them like "a kid". But still let them know that you have their back.
Show your own vulnerability. You are going to have to start treating them as equals if you want a good adult:adult relationship going forward in life. Stop acting like you are "in charge" ... but you still have their back

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