Step 1: Go to Services and select DNS Hosting
From here, you will see either DNS with Domain (free with domain) or DNS Hosting (for domains not renewed through Truly Cloud).
Step 2: Select the domain you wish to enable DNSSEC
Step 3: In the top right-hand corner, you should see Manage DNSSEC Please click it
Step 4: Select the encryption level you wish. We have defaulted to RSASH256, then click "Enable DNSSEC"
That's it you're now enabled with DNSEC.