Generally, you can only add a SSD in two scenarios: if it has a m.2 slot, or if has an optical bay where there is a disc drive currently installed. So, if you laptop has a disc drive, you may be able to find a kit that will let you mount a SSD in place of that, depending on the laptop.
Otherwise, you will have to replace your existing drive to use a SSD. Hybrid drives are ok if you value local storage, but if you're comfortable with other external solutions, I would avoid them. They're more like mechanical drives than they are SSDs.