This is an area where you just have to do the math. It’s not the number of bulbs, it’s the wattage of the bulbs, which will be listed on every bulb. For incandescent bulbs just count the wattage for each bulb. A 25 W chandelier bulbs should be counted as 25 W, where a 100 W bulb should be counted as 100 W.
The 1000 Watts cutoff applies to incandescent bulbs.
LEDs work differently than incandescents. A number of electrical site suggest just using a rule of thumb of counting any LED bulb as 100 W for the purposes of max load calculation. So a switch with a max load of 600 W could handle six LED Bulbs and a switch with a max of 1000 W could handle 10 LEDs. The operating wattage for the LEDs will be much lower, probably closer to 10 W, but the issue with LEDs and switches is that there’s a big jump in current when the bulb first comes on. So while your electricity bills will be lower with LEDs, the switch still has to be able to handle the startup sequence.
But always review the specific device specifications for any model that you’re interested in. If for whatever reason you don’t feel confident in doing that yourself, then enlist an electrician.