This lawn mower from Einhell can hold 45 litres of grass in its collection box. It has a minimum cutting height of 14 mm, great if you prefer a shorter lawn.
From Amazon
Einhell Power X-Change Walk-Behind Cylinder Lawnmower - 18V, 38cm Cutting Width, 45L Grass Box, 4 Cutting Heights, Mulching - GE-HM 18/38 Li Solo Battery Lawn-Mower (Battery Not Included)
Conrad Electronic
Einhell Power X-Change GE-HM 18/38 Li-Solo Rechargeable battery Reel mower Cutting width (max.) 38 cm