Charge for Creating database - Free Tier?

Hello.

When you create an RDS from the management console, an estimate of the monthly cost will be displayed even in the free tier.
The last price you see is the estimated monthly fee that you will begin billing when your 12-month free tier ends.
You can use the free tier for 12 months after your AWS account is created.
https://aws.amazon.com/free/?nc1=h_ls&all-free-tier.sort-by=item.additionalFields.SortRank&all-free-tier.sort-order=asc&awsf.Free%20Tier%20Types=tier%2312monthsfree&awsf.Free%20Tier%20Categories=*all

Don't worry, if you select "Free tier" in "Templates" when creating, you can configure the RDS configuration for the free tier.
https://repost.aws/knowledge-center/free-tier-rds-launch