It is essential to consider the issue of compatibility, which will naturally lead you to restrict your options. For example, it is possible to change from 50mm to 30mm tyres if your rim accepts this compatibility, but not the other way round. Check the maximum cross-sectional area that the tyre, wheel and frame can accept. In case of any doubt, contact your nearest dealer to make sure that the switch can be made without any unknown consequence.
Once you are aware of this constraint, you can choose according to your use. If you mainly plan to ride on sporty roads, for instance during training sessions, it is better to choose a MICHELIN Power Adventure with a smaller section (30mm), similar to road tyres and suitable for this use.
If you are looking for more versatility for your gravel bike, with 80% road use and 20% off-road use to have fun without too much risk of punctures, it is advisable to opt for tyres with larger sections, around 40mm, which will allow you to ride with lower pressures.
The advantage of having tubeless ready tyres is that you can ride safely with lower pressures without the risk of puncturing.
The closer you get to mountain biking, the more you should opt for wider sections. For example, MICHELIN Power Gravel tyres can be up to 47mm wide, while MICHELIN Power Adventure tyres can be up to 48mm wide.
By lowering your pressures, you will be able to regain good grip and better adaptability of the tyre to the off-road terrain you are going to cover. This combination of wider sections and lower pressures is ideal for off-roading.