I use Premiere pro cc 2018 and I can not export into youtube 1080p, the option is not there. I am on window.
They removed some of the 5,357 presets from previous versions ... thankfully.
Which format/codec combo do you want? H.264 in mp4 is of course heavily used as it is a smallish file to upload. A few here prefer DNxHD/R for a bit better quality and it typically gets displayed by YouTube without the color profile/gamma issues that can occur with H.264 uploads.
For 1080p say 23.976, minimum bitrate targets of 10 with max 12 may work, but settings a bit higher might be better. UHD/4K work takes bitrates 3-4 times higher of course.
Very easy to set. Oh, and skip the 2-pass export and un-check max bitrate and render depth.
And if you mean export to YouTube direct from PrPro, I and many others prefer to check the export before uploading anyway, manual uploads work easy enough for my taste.