I've used one of these for nearly 20 years, and it makes keeping clothing, particularly shirts, neat and tidy in any suitcase:
https://www.eaglecreek.com/products/...rment-folder-l
The external dimensions are 45 x 32 cm/17.75 x 12.5 in. The 'pack' has 4 triangular panels on the top, which open outwards to reveal the inner storage area. The base, or back, of the pack has a semi-flexible, rectangular plastic board in it, to aid rigidity. There is an additional, loose, plastic board as well, the purpose of which is described in the next paragraph.
Neatly fold your already-ironed shirts and trousers to fit the planform of the rectangular part of the pack, place the loose plastic board on top ofthem, and fold the 4 triangular panels inwards over it all, securing the panels with their velcro (hook and loop) closures. The 4 fold-out panels allow the closed pack size to be adjusted for varying amounts of shirts and trousers, thus preventing clothing in the pack from shifting and becoming more creased.
On arrival at your destination hotel, hang up the shirts, and any minor creases usually fall out in a few hours. You can speed up that process by hanging the shirt/s you next wish to use in the hotel bathroom, and the airborne moisture created by your first bath or shower does a great job of assisting the disappearance of any creases.
Iron the shirts at home, keep them on a hangar, and only (neatly!) fold and pack them shortly before departing for the airport (i.e. best
not to pack the shirts and leave them in a suitcase overnight). In 17 years of scheduled long-haul airline flying, using the above method, I never had to do any layover ironing, including those trips with multiple legs, where 3 or 4 uniform shirts were carried!
I also found the variously sized packing cubes, with zippered closures, to be great for preventing the suitcase contents from looking like they had done time in a cement mixer. Eagle Creek are not the only makers of such stuff, there are other manufacturers with very similar packing systems, but this particular garment folder was well worth the price for avoiding down route ironing!