Yes, it can be really good for recovery days. As mentioned earlier, it does depend on what you’re doing though. If you have a poor stroke and ‘fight’ the water and/or are doing hard efforts, whether long sets (depending on your fitness, 200s, 400s, 500s, 1000s) or sprints, well, that’s not going to help with recovery.
Because of all the muscles activated, especially if you’re doing it right or ‘nearly’ right, it’ll help increase blood flow, which is good.
Kicking, as stated, can be beneficial. You can do flutter kick (freestyle kick) with/without a board, on your side, on your back, etc. Also, add in breaststroke kick. Fly is probably tiring. I like to throw in egg-beater (from water polo) as it works other muscles, but for recovery, that might just be a half-length effort.
If you’re not confident with your swimming, I’d suggest your recovery swims first focus on technique with lots of technique-specific drills.
If the swim is recovery, then I’d recommend a rest-based intervale rather than a time-based interval. In other words, if doing 100s, it’s 5 x 100 with 15s rest instead of 5 x 100 on 1:30 (where the rest/send off is determined by when you finish). A complement to freestyle is backstroke, so you should insert that into the workout, even if just a part of the warm-up / warm-down. But breast and fly, both more technical, are great muscle and endurance strokes that will complement your overall swim strength and overall cardio, which will complement your run and bike.
Swimming will burn a lot if you’re doing it right. That means the right intensity, the right intervals, the right rest, right strokes, and right drills for the intended outcome. Because of the ‘fixed’ course nature of swimming, training has been a lot more scientific for a lot longer than cycling, which is ahead of the game (with TR as a lead) from running (where companies like Stryd are trying to make a difference).
And, if you don’t know how, please learn to flip turn (aka tumble turn). It will make your swim workout a better experience, and a better experience for your lane mates.