What happens if I forget to include www and how can I fix it

[cRen]

Friends, up until 2 months ago, I used my website starting with www. After a backup process, while making adjustments in the settings for https (wordpress), I forgot to include www, so currently it appears on Google without www. If I change it back to www, will our ranking change? I have keywords ranking in the 1st position and I don't want to risk losing them.