Something that I learned from a voice teacher, long ago, is that people sing off key to be heard.
If you sing well, you blend in with the music. People that sing slightly off pitch (flat/sharp) often do so because, subconsciously, they think they aren’t being heard well enough.
The human voice sits in the middle of the audio spectrum. If you need to be heard, a better choice is to find the tone knob and turn down the mid-range frequencies so that they don’t overlap with your singing.
Oh, there’s another thing. Practice. Thinking that you know a song is different than *knowing*a song. Don’t “wing it.” Know it and own it.