Most guests at BIG4 Toowoomba Holiday Park are here for work, a sporting competition, a medical appointment or a family visit — not sightseeing. But if your schedule does open up for an afternoon, Queens Park and the Toowoomba Carnival of Flowers are worth knowing about, particularly if you're only in town for a short stay.
Queens Park: an easy break

Queens Park is the obvious one — a large, established park close to the city centre with gardens, open lawns and mature trees, and it's an easy option if you just want somewhere to walk or let kids run around without much planning. It doesn't take a special trip to get value from it; even twenty minutes there is a reasonable break from a work day or a break between appointments.
Carnival of Flowers: timing your visit

If your visit happens to line up with September, the Toowoomba Carnival of Flowers is worth knowing about — it's a genuinely well-known regional event, and the gardens across the city are dressed up for it. It's not something to plan a trip around specifically, but if you're already here for other reasons and the timing works out, it's a worthwhile bonus rather than something to go out of your way for.
Beyond the city
Beyond the city itself, the wider Darling Downs region has scenic countryside if you've got more than an afternoon — better suited to a rostered day off than a quick break, given the drive involved.
For sporting groups with downtime between fixtures, Queens Park is close enough to the sporting precincts that it's a reasonable option for a team to stretch their legs or unwind without a big production. For families here for a medical appointment or a longer visit, it's an easy way to fill an afternoon without needing much of a plan.
None of this is essential to your stay — most people are in Toowoomba for a specific reason, and that reason is what your visit is actually about. But if a gap does open up, Queens Park needs no real planning, and the Carnival of Flowers is worth checking the dates for if you're here at the right time of year.
The takeaway: Queens Park is a five-minute option if you need a break, and the Carnival of Flowers is worth knowing about if your visit happens to line up with September — neither requires building your stay around it.