Here are query parameters of API GET /fixture:

• compIds is an array of competition ids that uses “,” seperator. Note: You can get competition info from GET /competitions API, it will return a list of competition data in which all clubs in Premier League are able to participate.
• clubIds is an array of club ids that also uses “,” seperator. Note: You can only query upcoming matches of selected clubs. If you need to retrieve more info about a club, you can use GET /clubs API.
• page & pageSize are two parameters that support pagination if needed. Default value is 0 & 20, respectively.