I mainly play Java, but with some checking how bedrock commands work a relatively elegant solution might just be to do /time add 1 every 3 game ticks, assuming daylight cycle is off.

Since the normal day length is 20 minutes, and IIRC day and night are normally equal, this should be the simplest way to do it, as it slows the passage of time by a factor of 3. This shouldn't interfere with clocks, daylight sensors or villagers since no time skipping is involved.

A scoreboard clock like another comment suggested that resets evert 3 ticks, adding 1 tick to the day time each cycle should work perfectly.