https://www.musical-u.com/learn/how-can-i-use-a-digital-tuner-to-practice-singing-in-tune/
One way to quickly improve your ability to sing in tune is to use a digital tuner.
These devices let you set a target note, hear that note, and then show whether your own note is above or below it and by how much.
They are normally used for tuning an instrument, but can actually be a very helpful tool for learning to sing in tune.
Read this article and learn how you can use a digital tuner to practice singing in tune.