A clear shower curtain will open it up.

Paint the entire room one color, ceiling too.

Neutral color walls with a white ceiling, and white and an accent color for the shower curtain.

If you want to keep the shower curtain, pick one of the lighter colours, the pink or turquoise/blue and paint the entire room with that.

Should I just get one of those cheap
Liners and cut it? The previous owners cut one and stuck it up there but it's crooked , maybe keeping the liner in the tub will help it look more symmetrical ?

If you don't want to keep this curtain, consider installing a glass panel.

See if a shower door company can do a glass panel for that triangle area. Good luck.

Would this not be enough?

I like that Carolins.... Maybe they have a shorter rod at the top that doesn't go across the whole shower ?

I think they may have use a painted wooden block mounted on the ceiling and a tension rod between wall and that block?

It goes the length of the ceiling and I don't think I want to keep :/

If the current shower curtain track and hooks are in good shape and well made, have a textured white curtain ( waffle weave or a tone on tone design) made for the space. This will give it a spa feel. Paint a soothing color on walls with white ceiling. You should be able to find a local seamstress to make a curtain inexpensively.

That's genius! Only
Problem is ours slopes all the well, we are in the process of buying it so I wish I took a
A better photo to see of I have any
Space for a curtain like that :)

i think you should go with a glass panel and not a curtain. a shower curtain will just make the room appear smaller. you could get a shelf above the toilet and shelves or a towel rod on the wall next to the toilet, might be too tight , not sure

I would do a light blue shower curtain and paint the walls the same color. Get maybe 1-2 paintings that have that blue color. Get rid of that big mirror and put one over the sink. Maybe but the big one on the back of the door.

Paint the room 1 color - maybe a shade of gray
I would change the sink - maybe a wall mounted sink with drawers underneath- you can keep a basket of towels underneath
If it's in the budget - get custom glass doors if not I would go with a very simple pattern complimenting the wall color
I find browns/ beiges and gray tones are very soothing for the bathroom