I have been in the same position, it's difficult to come up with a project. I think looking around and identify a small problem or interesting challenge that you think could be solved using the computational power of an Arduino. Also, if that is still difficult, it is ok for you to look online for existing Arduino projects that interest you and do your best to replicate them, or maybe change them slightly to fit your situation. There's nothing wrong with learning from duplication, and it would be valuable experience that may help you start thinking of your own project ideas.

Read the following book chapter

https://www.researchgate.net/publication/309558361_A_WoT_Testbed_for_Research_and_Course_Projects?_sg%5B0%5D=XoRb6ik6pMyJ7615m5ibemTl90JgPGY4Pb8VxmCBtDSQVzUriWlDhmCrUasZRd4159QPIIMtkmiFdgRqr6opddmgOYBMKOXt6IfnkHm0.e05t2_01ac9aVvfv3MvTGQnyMvIPBXG752T1gx3XDOpbi7w7_aEk0Nt5eQSmxKzjjf0YCwR8D3UnN_8leejHrg

here are some ideas

1- creating ad-hoc network using multiple Arduino

2- zero energy wireless sensor network using Arduino Nano

3- Audio/video output using Arduino Uno

4- Realtime 3D imaging using Arduino

5- flight simulator with force feedback using Arduino

6- data communication over power line for smart grid using Arduino

7- Arduino 3D digital input device for CAD/CAM

8- using Arduino to test circuits with certain test points

9- Arduino Health monitoring based on IOT

10- Motor shaft mis-alignment correction using magnets based on Arduino

11- impact parameter detection of polymer specimen (force, speed, bounce distance, etc)

12- automated medication delivery (vein) using micro pumps based on Arduino

13- home power redirection and appliance priority activation in solar based system based on Arduino

14- laser projection of 2d images using Arduino

this is from the top of my mind, hope it is useful