Start by measuring your available space to fit a desk around 100 to 120...

https://fast-wiki.win/index.php/Chartered_Institute_of_Ergonomics_Workstation_Tips_for_Gamers

Start by measuring your available space to fit a desk around 100 to 120 centimetres wide. Use a monitor arm to free up surface area and keep cables tidy. Make sure to leave enough chair clearance—about 60 centimetres behind—to move comfortably