Can I use a single dimmer switch to control multiple lights?
A given switch has a specified limit on the total power it can control. Add up the total wattage of all the bulbs and if this is less than the limit for that dimmer, then it should work. Note that for LEDs you use the actual wattage not the equivalent wattage for an incandescent which gives the same illuminance (lumens).

Also the dimmer switch must be one which is designed to control LEDs. A dimmer switch from decades ago probably won't work. For years I used a 30 year old programmable dimmer which was approved for incandescent bulbs to control an LED by using one incandescent and one LED in the two bulb fixture.