Extreme etiolation - it is likely in very low light for quite a while. It cannot be 'repaired', only starting new plants from cuttings and keeping them in good light will produce more compact plants.

If you give it more light, you will see the new growth start to become stouter and more compact. The rest of the plant will remain "stretched".

If you search online for pics of graptosedum or graptoveria, or maybe pachyveria (but probably not), you will see pics of what they will look like in optimal (high light/good soil environments).

Right now your plants look like they like the soil and watering (your soil looks kind of peaty, which may lead to root rot), but need more light.

Can I trim it back? Or put in more light and let it do its own thing? It was outside last summer and on a windowsill this winter.

If you leave it as is, the stems may be too weak to hold up. Best would be to prune them and pot all the prunings for new plants. I would leave original stems in the soil 'cause they may grow babies either from the stem or from the roots - I am not sure what the plant is, so can't tell. And definitely put all in more light to avoid same stretching, just acclimatize them to more light.Here is one of the succulents that grows easily from stem after being 'beheaded' (this is Graptoveria 'Fred Ives'):