Day trips from Ronda

Not a direct response, but we found that Gibraltar was too far for a car daytrip. Roads were good but truck traffic slowed progress. We also gave up on Zahara (Seville to Ronda day) becausevit was soooo far off the "highway."

I can’t offer any advice as to best day trips from Ronda because we didn’t make it there and only traveled via public transportation while in Andalucía.

Since your next destination is Granada.
Have you already booked your Alhambra Tickets?
If not, you may want to do so ASAP!

Alhambra tickets may be booked 3 months in advance, and they sell out rather quickly during high season.

Are you planning to visit Córdoba and Sevilla as well?

Enjoy your trip!

Edited to add…
Here’s a post from 2019 that you may find helpful: Day trip from Ronda to Zahara de la Sierra

I haven't been to Zahara de la Sierra. Grazalema (population 1400) needs less time than Arcos de la Frontera (population just over 30,000), and Grazalema (population 2000) is close enough to Zahara that I think you could visit both in one day. All three are visited primarily for their picturesque streets rather than for indoor sights. Arcos is probably too far west to be a smart day trip from Ronda; the driving time is estimated at 83 minutes, but the walking time up from where you'd want to leave your car would add to that.

Malaga is a large city of over 550,000; Ronda's population is 34,000. Malaga's very attractive, but I don't think such a large city is very practical for a quick stop, particularly just for lunch. I think a small town would be better. However, if your next stop is Granada, traveling by way of Malaga will add only about an hour of driving time, per ViaMichelin.com. Finding a place to park the car and walking to what you want to see, or to a restaurant, would increase that time. The folks on the forum who've been to Antequera have really liked it, and it would be much less of a detour on the way from Ronda to Granada. It's small enough (population 41,000) that a stop shouldn't be too awkward.

Grazalema + Zahara de la Sierra make for a great day trip from Ronda - you can definitely visit both in a day, they are small.
Picturesque roads, too - if a bit hairy between Grazalema & Zahara.

As Balso said, the road between Grazalema and Zahara de la Sierra is hairy. The distance is only 10 miles, but it will take you about 30 minutes to drive due to the twists and turns. If all you wanted to do is drive by the white towns and see them from a distance, you could do a circular route between Ronda and Arcos de la Frontera. You could also take the short trip up to Sentenil de las Bodegas. In Zahara de la Sierra, we parked by the tower that overlooks the reservoir. Unless you plan on engaging in outdoor activities like hiking, the towns don’t take long to see individually.

We just did Zahara and Grazalema as a day trip from Ronda this past week. You can easily visit both in one day, we had time to climb the tower in Zahara and eat lunch and wander the streets of Grazalema and were still back at our hotel by 3:30pm. The road is definitely hairy! My husband coaxed our little Fiat up and down the hills but it was stressful -- especially for him as he has mild vertigo and the road between the two cities is entirely switchbacks up side of the mountain. If you can rent something with slightly more power than a manual Fiat 500, I would encourage you to do so.

We also didn't make it to the Pileta Cave but it looks amazing and is just outside Ronda. It is on my to-do list for my next visit to Southern Spain.