Use the direct selection tool to select Your points and as long as these are Corner points you can click and drag This roundway just to adjust the Roundness you can also use the settings From the control panel and using these Buttons you can adjust the corners type Or the rounding style going to window And properties will open the properties Panel where you can find the same Settings Keep in mind that the settings can only Be used for Corner points when dealing With smooth points you can either use The Anchor Point tool to adjust the Roundness Or you can use this button to turn your Smooth points into Corner points and Then you can use the widgets to adjust The roundness using this other button You can turn a corner Point into a Smooth point to apply round corners Using an effect go to effect stylize and Round corners set the radius and click OK finally even masks can have round Corners we'll use this rectangle to mask The photo and then using the direct Selection tool you can adjust the Corners radius of this mask