Hello I need help to unlock my 16 plus T-mobile this is the imei: 35 099154 290644 7

Are you a T-Mobile USA customer?  Are you sure the device is SIM locked to T-Mobile?  Does your T-Mobile account and device meet all of the SIM Unlock Policy requirements?

SIM Unlock Policy | Unlock Your Mobile Wireless Device | T-Mobile https://www.t-mobile.com/responsibility/consumer-info/policies/sim-unlock-policy