AWS Free Tier - Account Closure

Yes, if you don't accrue any charges then you won't be charged anything.

Be aware that not everything is free, and of the items that are free, not all of them are free for 12 months. Some are free (with limitations) for 12 months e.g. EC2, RDS, S3; some are free (with limitations) for shorter - e.g. Lightsail (3 months), Redshift (2 months), Macie (30 days). See https://aws.amazon.com/free/

But if this is your first experience of AWS and you just want to try things out, it's usually quite easy to stay within the free tier limits. Just be conservative when creating things and remember to clear things down when you're finished with them. You could also setup a CloudWatch alarm (you get 10 of them for free within free tier) to warn you if it looks like you're starting to accrue charges https://aws.amazon.com/cloudwatch/pricing/?loc=ft#Free_tier