Hi davout,
Yes the functionality is achievable by using --smart-scheduler-timeline-header-all-day-cells-size CSS variable and set it depending on how many task you have in the row.
Quick code snippet showcasing how to use this CSS variable:

.smart-scheduler {
    --smart-scheduler-timeline-header-all-day-cells-size: 200px;
    width: 100%;
    height: 100%;
    --smart-scheduler-view-item-size: 100px;

More about the Scheduler component’s CSS variables you find in the documentation:
Let me know if that works for you!
Please, do not hesitate to contact us if you have any additional questions.
Best regards,
Yavor Dashev
Smart UI Team