Low-cadence intervals, for example 50-60 rpm at tempo or sweet spot power, are sometimes promoted as “strength on the bike”. The evidence on what they actually do is mixed.
The force per pedal stroke is higher at low cadence, but it is still far below what a squat or leg press demands
Some riders like them for building comfort with big gears on climbs and in headwinds
They are not a substitute for strength training in the gym
Very low cadences under high load can stress the knees, especially if bike fit is not ideal
If you want to try them: 3-4×8 minutes at tempo power (about 76-85% FTP) at 55-65 rpm, seated, with 4 minutes easy at normal cadence between. Stop if you feel knee pain. Treat it as a variation, not a key session.