There are many mystery shopping companies that post phone and online shops. Do not fall for scams in this arena! Check if a company is reputable. The MSPA has a list of companies you can trust.
https://www.mspa-americas.org/search/
For clearing house and collective shops in one app, look to Gigspot (https://gigspot.com/) or iSecretShop (https://www.isecretshop.com/), both, as well as many others, offer a section for phone and online shops to be posted. Register with the company and apply or self-assign the shops. These are great when the weather is bad or you are caring for children or parents and can't leave the house. The pay is usually about $2-50, depending on what you need to do.
Make sure you meet the technology required for each shop, the guidelines will specify how the shop is conducted. It is important to meet all criteria if you wish to be paid. As you get started, take simple shops, learn the ropes!
If you have any questions on any type of mystery shop, drop a comment, I can answer them!