audio – Ffmpeg webm YouTube settings command

Is there a .webm still image command in ffmpeg that is best compatible with YouTube I’m currently using:

ffmpeg -loop 1 -framerate 2 -i input.png -i audio.m4a -c:v libx264 -preset medium -tune stillimage -crf 18 -c:a copy -shortest -pix_fmt yuv420p output.mkv

But I want to know if there is a specific still image .webm YouTube settings? Can someone help me by giving me the command

I’ve found this:

ffmpeg -i “input.png” -i “audio file” -c:v libvpx-vp9 -lossless 1 output.webm

But not sure if that is the best compatible YouTube settings