Can I extend my 30-day free visa for Thailand multiple times, and what are the PCR testing requirements upon arrival?

Hi folks, a kind gent pointed me in this direction as I was asking about Thai visas on another page. I'm from the UK so I get 30 days free visa, can someone answer are you limited to how many times u may extend for 30 days from withing Thailand? I did it once about five years ago. My wife (indonesian) will be travelling with me and also has the 30 days free so we will likely want to stay longer. Unfortunately her employer is causing us some issues and we've ran out of time to apply for propper visas at the embassy as we will arrive in Thailand on the 30th of this month. - side question if you wouldn't mind answering, we will get our pcr before departure, fly to phuket.. Do we get a pcr test on arrival or is that something that I'm supposed to prebook? Thanks for any help im a bit useless when it comes to this stuff 👌