Ragavendiran,
This option is not available through EXOS or RADIUS, per the following article:
https://gtacknowledge.extremenetworks.com/articles/Q_A/Can-you-have-per-user-allowed-command-permissions-when-using-a-radius-server-for-authentication
The following post does give some insight on privilege levels using TACACS:
https://community.extremenetworks.com/extremeswitching-exos-223284/xos-restrict-cli-commands-6856140
Privilege levels are handled by RADIUS on the server side. On the RADIUS server a normal user is needed for user access. If the user needs admin privileges on the switch the RADIUS user should be configured to send the RADIUS Service-Type attribute with a value of Administrative. For further information on this attribute, see
Section 5.6 of RFC 2865.