In theory, yes, but it depends what your goal is. If your goal is to simply get experience at configuring sendmail and testing if it works, then yes, it is technically possible to run it that way.
If your goal is to actually run a functional mail server on which you or others will depend for mail receipt, then probably not. At the root of things, if you are sending email from a domain literal (IP address) rather than a domain name, you will look like a spammer and mail will generally not be accepted by remote servers. Further, without an MX record, even more mail servers will fail to send you messages.
Finally, if you do not have a domain name, then chances are that your sendmail-reported hostname will not have a DNS record to look up and your IP address will not have a reverse DNS record pointing back to the sendmail-reported hostname. More rejection from remote mail servers.