There is such a window component that holds the hinge side of a casement tight and it's typically found on the exterior side of the sash when it is closed.
The component is called a snubber (different from an anti-jemming) and can either be made of PVC or Aluminum to match the exterior finish of the window. (Additional link 1)
Though snubbers are intended to prevent bowing (see item description) of an outswing-casement, they can also be used to ensure that the sash is close to the frame when closed. However, snubbers are not the only elements that help the sash seal better. The weatherstripping and the casement hardware also determine how tight it is and you can contact the window's Service Technician to adjust the operator arms/hardware of the casement sash without having to replace either/both the weatherstrip or hardware.
Though, depending on what kind of operator handle you have, you can remove the handle and reattach it at a slightly rotated position from where it originally was. However, please do this at your own discretion as over-tightening the sash can cause issues related to the performance of the casement and/or damage the operator hardware if the seal is too tight.
Note: The operator handle solution below is only applicable to crank-out style casements. If the window you have is a Euro-style (turn and/or tilt with handle) contacting a Service Technician for adjustments is recommended.
(Pictures of your window are needed to better address the sealing issues you have with it.)
[Update] In the event of your window being a Euro-styled window, with a multipoint locking system, you would need to adjust/re-calibrate the Compression Strikers, Turn[/tilt] Strikers, and Lift Mishandling Device(s) attached to the inside perimeter of the frame. Without proper training or tools, however, maintaining consistent alignment on all four sides of the sash can be difficult and may compromise the weatherseal of the window.
A final solution are hinge wedges/pull in blocks.
They work almost identically to the snubbers at the top, however these wedges are concealed within the sash/frame void and slide against each other to "pull in" the sash.