no, you have to run "restic forget" with the policy you want (keep last X, last monthly Y, etc.) followed up with a "restic prune". Or you can pass "--prune" to the "forget" command I think.
You don't always want to forget/prune snapshots. Especially if you're using a cloud service like B2. It can easily cost you more to prune than actual storage costs if you're not careful.