Hi @rg@bn
No, If you want to use Mp1 clients, you can install them without upgrading to SEPM to MP1 version, you need to download the client packges from fileconnect
Make sure that your OS has supported by MP1 package -
https://support.symantec.com/en_US/article.INFO4192.html#SEPWin
Upgradation of SEP manager to SEP 14 MP1 -
https://support.symantec.com/en_US/article.TECH236071.html?redirect=false#upgrade