A tub/shower enclosure is about 2'x5'. I cannot imagine wanting a shower smaller than that, especially if, in lieu of a shower curtain that moves, the door is solid and fixed. In fact, 3'x4' or even 3'x5' would be better. You need to be able to bend over and touch your toes without bumping your head. My 6'2" brother had one of those 3'x3' for a time and hated it -- you'd have to use a long handled back brush to wash your feet.

New build, reno, addition? Can walls, door, window move?

800x800mm is generally the minimum standard size for a shower. I think the code is slightly less than that. Code is not comfort though. 900x900mm is a far more comfortable size.
I disagree entirely with the above comment. There's clearly no space for a 5foot shower here. That's luxurious. Not minimum. 3x3' leaves a diagonal length of over 4'.

You need 540mm, if I recall correctly, clearance space in front of the toilet to the shower.
So working with your current proposed layout;
800(shower) + 540(clearance) = 1340(shower+clearance)
1800(available) - 1340(shower+clearance) = 460(available for toilet)

Most toilets are considerably longer than that.

You also have a tightish spot between the vanity and shower corners, but it should be manageable.

Switching the toilet and shower (and rotating the toilet) would be a better layout, but windows in showers are generally problematic

Switching the vanity and shower may work better too.

If that is your plan above and you have not quite a 6' x 6' foot bath, you really have a problem. It is too small for all three elements. Period.

Find two feet on the long wall.

My home had a 5.5' x 5.5' master bath, which was the height of luxury in 1924 when the house was built! It was incredibly tight with a corner neo-angle shower (24" x 24") and a corner sink. Make it bigger if at all possible, or just have a sink and commode and use it as a powder room.

Min shower size is 30" X 30" and you should have 24" clearance in front of the opening. In front of the toilet or vanity, you need 21" clearance.

I would probably do something like this