Everyone wants their furniture to be comfortable, but if your furniture "eats you alive," anyone would have difficulty climbing out of it, especially if that person is elderly and is deconditioned. Therefore a simple principle to apply no matter how tall or short a person is that if their hips are slightly higher than their knees, it will be much easier and less physically demanding for a person to come from sitting to stand.
You can raise the seat height, particularly on the couch or favorite chair, by using additional cushions, densely folded blankets, or risers underneath the furniture. Ensure they are stable and not shaky when the person goes to sit, such as rocker recliners or wheeled seating.
For example, when a rocker leans forward, the front seat height is lower to the ground, making it difficult for a person to come from sit to stand. You can place thick books or blocks of wood under the chair, on the floor just below the front of chair's arms to prevent rocking action.
Don't rush out to buy a lift chair either as these can rob your loved ones ability to strengthen their leg muscles to be able to move from sitting to stand, or unless you have a lift assist for all other transfers, such as toilet, care, shower, bed or shower- I would avoid these chairs and ask your healthcare provider to send your loved one to a Physical Therapist for strengthening.