Delta Chat does not have spam reporting and “platform moderation” tools because it is essentially peer-to-peer, the clients exchange messages with each other.
Unlike messengers that have discovery by phone number, your profile is not discoverable without you sharing a QR code or invite link or one of your contacts sharing your contact to someone else. Most problems with having your contact shared too widely can be avoided by having separate profiles, e.g. your family profile and your “public” profile in case you need to share it to strangers.
If you use chatmail relay, you also cannot receive unencrypted mails and your email address is random, so nobody except the relay operator can send you unencrypted spam. We also want to add an option to drop incoming unencrypted messages and enable it by default as a protection against unencrypted spam: