Stance width can vary with a sumo DL. Some prefer toes near the plates. Others prefer a more narrow stance to get more drive off the floor.
Make sure your arms are inside your legs. The bar should be just over your mid-foot. Flatten your back and push your heels into the floor.
Try to extend your knees and hips simultaneously.

Barbell Sumo Deadlift: A Comprehensive Guide

Setup

Start by selecting an appropriate weight on the barbell
Position the barbell in front of your feet, making sure it is centered and directly under the bar
Stand with your feet slightly wider than hip-width apart, with your toes pointing outwards
Bend your knees and lower yourself until your shins touch the bar
Grip the bar with your hands, making sure they are positioned just outside your feet
Take a deep breath and tighten your core muscles to prepare for the lift

Lift your chest, straighten your back, and look forward
Begin by driving through your heels and pushing your hips forward
Lift the bar off the ground by extending your hips and knees
Make sure to keep your chest lifted and your back straight throughout the lift
Once the bar reaches knee height, pause briefly before continuing the movement
Lower the bar back to the ground by reversing the movement, bending your hips and knees
Repeat the exercise for the desired number of repetitions

Keep your feet flat on the ground and maintain your balance throughout the exercise
Avoid rounding your back, as this can cause injury and decrease your lifting efficiency
Keep your core tight and maintain good posture to prevent your lower back from arching
Use your legs and hips, not your arms or back, to lift the bar off the ground
Do not drop the bar, but rather control the descent back to the ground

Using too much weight that may compromise your technique and increase your risk of injury
Rounding your back or allowing your hips to drop too low during the lift
Bouncing the bar off the ground, as this can cause strain on your lower back
Lifting with your arms instead of using your legs and hips
Forgetting to warm up properly before starting the exercise