Assuming you are in San Diego, CA. There are many options available. Nursery have semi dwarf trees, dwarf trees, and also "grafted" trees which have fruits (grapefruit/orange/lemon) as low as 2 feet tall and 2 feet wide. The nursery grows from seed a "base" tree which is appropriated to the weather and soil of the region. When the base tree is a few or several years old, the main trunk is cut off above the ground, and they "graft" (connect) a mature branch of another tree (of the same family species) which has the desired fruit into this base tree. The result is the customers have the tree at super low and have desired fruit instantly (or within a year or two).
If your yard is limited in size, you can choose to go the dramatic ways: How about 5 different fruits in one tree. Some nursery call them "salad bar" trees or "cocktail" tree. You have multiple mixed and match of different kinds of apples in 1 apple trees. Or multiple different of peaches, nectarines, plums in another tree. The mix-math is unlimited as long as they are in the same family of the tree species.
For the tree's height, if you keep trimming the tree you can control its height, and do not need a ladder to harvest your fruits.
More info and explanations available here:
There is one re-seller in the South East San Diego who has a fairly size collection of these grafted trees. The benefit is that you can see it, touch it, and do a limited selecting, before taking your tree home, instead of waiting for the UPS to deliver your unknown tree.