Hello can you please guide me what should i do now my phone gets off after some time

Depending on how old it is, it may be time to replace your battery.

Batteries degrade over time with usage, that's just how they work.

You can expect about a 1% drop per month with average use on an iPhone.

Apple recommends replacing it when it reaches 80%. To check your battery health, go to Settings > Battery > Battery Health.

iPhone Battery Replacement.

iPhone Battery Repair & Replacement - Apple Support

Do you mind please elaborating a little bit about your question? I do not understand what you mean by get off sometimes. If you are referring to sometimes the actual little quirky we’re not get online through Wi-Fi or running slow. First I recommend powering off your phone for five minutes daily that will clear out any kind of cookies or anything that might be in bedded in the phone. Next as a daily task I also turn on airplane mode for about three minutes and then I will turn it back off and it clears out a lot of little bugs that are happening at the time with my phone. If this is not what you were looking for respond and clarify exactly what you mean so I would be happy to help you