I assume you mean their bosom, not their chests. First some reactions to other answers. I would be careful about wider angle lenses as it makes them look less attractive in general. Poses and clothing can do a lot. And using a model with a bigger bosom helps a lot, too. However, post editing is often applied in the professional world. In photoshop liquify [LINK] can be used, and some free software have similar tools. That type is most often seen used to thin the chins and waistlines of the models (there's a wide range of videos showing how to make a jane doe look like a "supermodel" - often used by women on facebook to fight low self-esteem).

I once made a video on how to use that kind of tool in the opposite way [LINK].

And used it to show that the pick for wonder woman isn't so bad as people claim (includes bosom enlargement, but it is a bit roughly done - I made it for a nerd page as a joke):

I assume you mean their bosom, not their chests?

Firstly, some reactions to other answers: I would be careful about wider angle lenses as it makes them look less attractive in general. 

Poses and clothing can do a lot. And using a model with a bigger bosom helps a lot, too. However, post editing is often applied in the professional world. In Photoshop, liquify can be used, and some free software has similar tools. That type is most often seen used to thin the chins and waistlines of the models (there's a wide range of videos showing how to make a Jane Doe look like a "supermodel" - often used by women on facebook to fight low self-esteem).

I once made a video on how to use that kind of tool in the opposite way.

And used it to show that the pick for wonder woman isn't so bad as people claim (includes bosom enlargement, but it is a bit roughly done - I made it for a nerd page as a joke):

I assume you mean their breasts, not their chests. First some reactions to other answers. I would be careful about wider angle lenses as it makes them look less attractive in general. Poses and clothing can do a lot. And using a model with bigger breasts helps a lot, too. However, post editing is often applied in the professional world. In photoshop liquify [LINK] can be used, and some free softwares have similar tools. That type is most often seen used to thin the chins and waistlines of the models (there's a wide range of videos showing how to make a jane doe look like a "supermodel" - often used by women on facebook to fight low self-esteem).

I once made a video on how to use that kind of tool in the opposite way [LINK].

And used it to show that the pick for wonder woman isn't so bad as people claim (includes breast enlargement, but it is a bit roughly done - I made it for a nerd page as a joke):

I assume you mean their bosom, not their chests. First some reactions to other answers. I would be careful about wider angle lenses as it makes them look less attractive in general. Poses and clothing can do a lot. And using a model with a bigger bosom helps a lot, too. However, post editing is often applied in the professional world. In photoshop liquify [LINK] can be used, and some free software have similar tools. That type is most often seen used to thin the chins and waistlines of the models (there's a wide range of videos showing how to make a jane doe look like a "supermodel" - often used by women on facebook to fight low self-esteem).

I once made a video on how to use that kind of tool in the opposite way [LINK].

And used it to show that the pick for wonder woman isn't so bad as people claim (includes bosom enlargement, but it is a bit roughly done - I made it for a nerd page as a joke):