How can I spray a plant for bugs before bringing it indoors?

See if these help you!

https://getbusygardening.com/debugging-and-cleaning-potted-plants/

https://homeguides.sfgate.com/treat-houseplants-before-bringing-inside-winter-97859.html

https://www.hometalk.com/diy/outdoor/pest-repeller/q-how-do-i-debug-large-house-plants-before-bringing-them-inside-this-fal-32050217

Remove the drip tray from beneath the plant. Remove any debris from inside the drip tray and wash it in clear water. Insects and pests may nest between the pot and the drip tray.

Knock the bottom of the pot against the ground to dislodge pests in the soil. Some pests, like beetles and millipedes, don't like the disturbance and will scurry from the soil. Don't knock so hard that you break the pot.

Inspect the leaves and stems, paying special attention to the underside of leaves where aphids, scale and mites like to feed. Dip a cotton swab in alcohol and rub it across any visible insects or eggs to kill them.

Set the pot back on the drip tray. Bring the plant inside and place it in an area away from other indoor plants to prevent any remaining pests from spreading to you pest-free houseplants.

Keep the plant separated from the other plants for two to three weeks. Inspect the plant daily for signs of insects during this time. Treat any insects with a pesticide specific to the pest, following the insecticide label application directions.

Plants may suffer shock and wilt when you first bring them indoors. Begin bringing the plant indoors for two to four hours a day two or more weeks before frost, and keep the plant in a brightly lit indoor area to minimize shock. Gradually increase the time indoors over the two week period to help the plant acclimatize.