This kind of top is rather large and can fit someone with a size between the French sizes 38 and 44.
The sewing allowance (the space between the edge of the fabric and the sewing) is narrow: 0.5 cm.
For a tighter effect, enlarge it.
Fold two pieces of kimono sleeves of the same size and put them one upon the other.
On the left, put a wonder clip at 22 cm from the edge of the upper part. This will be the opening for the top sleeve.
Still on the left, put another clip at the bottom, for the opening of the start of the cleavage (25 cm in this case).
To get the two pieces together in the center, sew from the clip down to the bottom.
Do likewise on the other side. I have left 5-6 cm from the top for the opening.
The two pieces that have been folded and attached to one another should look like this.
Attach the sides on the left and right by sewing from the clip to the bottom.
At the bottom, cut off the unnecessary bits.
Iron and flatten the 4 seam lines (2 in the middle and 2 on the sides).
Try the top on to make sure the size of the cleavage satisfies you.
If you are happy, prepare the field for the sewing with the needles.
If possible, sew in one go.
I have used metallic threads on the surface. So in that case, you need to sew on the front side.
Do likewise for sleeves.
At the bottom fold 3 times if you do not use any bias tape and keep your work from moving with clips.
Sew on the front side if you still use metallic thread.
To reinforce every opening, sew a thin horizontal line 3-4 times.