Broadband is sold on download speed, which for most households stopped being the limiting factor some time ago.
What things actually use
High-definition video streaming: around five megabits per second per stream. Ultra-high-definition: around twenty-five.
Video calls: a few megabits.
Gaming: very little bandwidth, and latency matters enormously.
Browsing and email: negligible.
A household streaming two ultra-high-definition videos while someone is on a call and someone else is gaming needs perhaps seventy megabits. Connections of several hundred are sold as necessary.
What actually matters more
Latency, which determines how responsive everything feels. A connection at fifty megabits with low latency feels faster than one at five hundred with high latency.
Upload speed, which many connections treat as an afterthought and which determines video call quality and how long it takes to back things up or send large files.
Consistency. A connection that delivers its advertised speed at ten in the evening is worth more than one that delivers twice that at four in the morning.
Why your wifi is probably the bottleneck
The connection into the house is frequently faster than what reaches your device. Distance, walls, an old router, or a crowded channel all reduce what you actually get.
Testing on a wired connection tells you what you are paying for. Testing on wifi tells you what you receive.
The practical advice
Work out your realistic peak, add margin, and spend the difference on a better router or a mesh system rather than on a higher tier.