A picture looking at the front of the house would help.

I’ve added a few photos to help

Before turning the walk into concrete, you might want to consider moving it farther away from the house. Shrubs that would fit your windows could easily take up the landscape space AND the entire walk, if you were to trim them in some normal mounded shape. If you want to pinch them into a squared off hedge, you're all set for that now.

Thanks yardvaark. Unfortunately we can’t move the walk any farther from the house as that’s the beginning of the septic system. We won’t be using concrete either... likely something more natural like stone.

Is there something else that would work? Would plants in pots be more restrained in how large they grow?

Go to good local nursery for advice. Give them your requirements, show them the pictures, and ask for suggestions. You can see the candidates "in the flesh" and decide what pleases you.

Plants in pots not practical. You'll need to do like everyone else (tight beds are commonplace) and trim to keep the plants within bounds. This tends toward squared off hedges or shrubs, but the shape can be controlled by you to a large degree. In general, (I think rounded looking shrubs and hedges look better.)

Here's an example of a general way of organizing trees and shrubs. (There is a second tree along the street, but the photo doesn't allow it to be fully shown.) The lawn/turf is not painted in.

Yardvaark thank you! It’s quite nice. I like the tree but it would destroy the septic system below it.

the house is symmetrical and I’d like a complementary style that’s not too stiff and formal looking

It's really too bad the septic system is right in front of the house - while the tall foundation does call for foundation planting you'll never be able to marry the geometrically symmetric house façade to the naturalistic setting without being able to have plantings that echo the façade design extending out from the house. To form a transitional zone between these two dominating elements (the design of the façade and the setting within which it is being viewed).

In the above mockup the white flowered bush to the right serves only to underscore the void between the style of the house and the surrounding setting, rather than tying the two major features of the property together - being able to continue the formal foundation planting, with its matching pairs with some kind of geometrically symmetric design out across the lawn would do so much more to produce cohesion.

"I like the tree but it would destroy the septic system below it." Shrink the tree size to whatever works ... large shrub. Any overhead canopy, even if small, is better than none.

Dig Doug that looks great!