Is it ok to join art school not knowing how to draw?

Art schools will, by and large, require that you submit a portfolio in order to get in, and that will include drawing. However, you can always plead your case, and tell them you wish to learn to draw. Maybe that will help.

The irony is that until very recently, in the past many decades most art schools have not been teaching much in the way of drawing, focusing instead on the expressive aspects of art. This has given us some lamentable gaps in foundational artistry. Now, however, the pendulum has swung back, and emphasis on basic skills seems to be returning, thankfully.

If you gain admission to an art school, and study well, you will learn techniques, and most importantly, your efforts will be critiqued. Will this make you a better artist? Most probably, it will improve you. But artistry is a combination of technique and creative imagination. And creative imagination has to be fed from other sources than art school.