i am using esim using ios version 14.8 and when i update it ios 15 then my esim still available after ios 15 updated

I guess you mean that your eSIM is NO LONGER available after iOS 15 update.

Should be this case, two things to try:

Try a forced restart of your device:--> Force restart iPhone – Apple Support

and/or contact your eSIM provider and see if they have an update for your eSIM.

If you mean something different, please better specify your needs

Regards

Giulio