Hi!
I'm currently doing adv Higher French, if you want to take it you totally should!
There is quite a big jump between levels but it's not unmanageable and your teacher/lecturer will support you through that, the main differences is just the level of grammar and vocabulary needed, but either your teacher or lecturer (if you go the online college route for it (I did)) will cover all that, the main thing is to just take a lot of notes/photos of the content.
There's also a portfolio, around 2000 words written in English that's worth I think 15% of the grade, but like it's nothing to stress about and the actual writing part of the exam is a bit different but with enough prep it isn't too difficult.
It's also just dependent on the time you'll have to do the course, so don't overload your S6 timetable with too many subjects and you'll be good! (I'm currently doing adv Higher French/German and then 2 highers, it's quite stressful so if you can do 3 subjects, then definitely only do three ^^)
Hope this helped a bit!