Hi there are multiple DIY solutions on the market such as Amazon Alexa, Apple HomePod and Google Nest.
As for my experience I have to say that DIY solutions are very simple, you can integrate them pretty quickly with the home system but they can control barely lights and audio.
There are some great companies that do professional smart home automation installations. Read this guide which contains lots of useful info on how to automate your own home https://www.intellicasa.co.uk/post/the-ultimate-guide-to-smart-home
Let me know if it helps.